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113 results on '"N. A. Baltzell"'

1. Observation of Azimuth-Dependent Suppression of Hadron Pairs in Electron Scattering off Nuclei

Author

S J, Paul, S, Morán, M, Arratia, A, El Alaoui, H, Hakobyan, W, Brooks, M J, Amaryan, W R, Armstrong, H, Atac, L, Baashen, N A, Baltzell, L, Barion, M, Bashkanov, M, Battaglieri, I, Bedlinskiy, B, Benkel, F, Benmokhtar, A, Bianconi, L, Biondo, A S, Biselli, M, Bondi, F, Bossù, S, Boiarinov, K-Th, Brinkmann, W J, Briscoe, D, Bulumulla, V D, Burkert, R, Capobianco, D S, Carman, A, Celentano, V, Chesnokov, T, Chetry, G, Ciullo, P L, Cole, M, Contalbrigo, G, Costantini, A, D'Angelo, N, Dashyan, R, De Vita, M, Defurne, A, Deur, S, Diehl, C, Dilks, C, Djalali, R, Dupre, H, Egiyan, L, El Fassi, P, Eugenio, S, Fegan, A, Filippi, G, Gavalian, Y, Ghandilyan, G P, Gilfoyle, A A, Golubenko, G, Gosta, R W, Gothe, K A, Griffioen, M, Guidal, M, Hattawy, T B, Hayward, D, Heddle, A, Hobart, M, Holtrop, Y, Ilieva, D G, Ireland, E L, Isupov, H S, Jo, R, Johnston, K, Joo, S, Joosten, D, Keller, A, Khanal, M, Khandaker, W, Kim, A, Kripko, V, Kubarovsky, V, Lagerquist, L, Lanza, M, Leali, S, Lee, P, Lenisa, X, Li, K, Livingston, I J D, MacGregor, D, Marchand, V, Mascagna, B, McKinnon, Z E, Meziani, S, Migliorati, R G, Milner, T, Mineeva, M, Mirazita, V I, Mokeev, P, Moran, C, Munoz Camacho, K, Neupane, D, Nguyen, S, Niccolai, G, Niculescu, M, Osipenko, A I, Ostrovidov, P, Pandey, M, Paolone, L L, Pappalardo, R, Paremuzyan, E, Pasyuk, W, Phelps, N, Pilleux, D, Pocanic, O, Pogorelko, M, Pokhrel, J, Poudel, J W, Price, Y, Prok, B A, Raue, T, Reed, M, Ripani, G, Rosner, F, Sabatié, C, Salgado, A, Schmidt, R A, Schumacher, Y G, Sharabian, E V, Shirokov, U, Shrestha, P, Simmerling, D, Sokhan, N, Sparveris, S, Stepanyan, I I, Strakovsky, S, Strauch, J A, Tan, R, Tyson, M, Ungaro, S, Vallarino, L, Venturelli, H, Voskanyan, E, Voutier, X, Wei, R, Wishart, M H, Wood, N, Zachariou, Z W, Zhao, V, Ziegler, M, Zurek, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and CLAS

Subjects
nucleus: size, carbon: target, lead: target, electron nucleus: scattering, Settore FIS/04, Nuclear Theory, hadron hadron: angular correlation, General Physics and Astronomy, nucleus: yield, FOS: Physical sciences, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], multiple scattering, angular dependence, CLAS, deuterium: target, iron: target, High Energy Physics::Experiment, hadron, electron: beam, Nuclear Experiment (nucl-ex), Nuclear Experiment, nucleus: surface, experimental results
Abstract

We present the first measurement of di-hadron angular correlations in electron-nucleus scattering. The data were taken with the CLAS detector and a 5.0 GeV electron beam incident on deuterium, carbon, iron, and lead targets. Relative to deuterium, the nuclear yields of charged-pion pairs show a strong suppression for azimuthally opposite pairs, no suppression for azimuthally nearby pairs, and an enhancement of pairs with large invariant mass. These effects grow with increased nuclear size. The data are qualitatively described by the GiBUU model, which suggests that hadrons form near the nuclear surface and undergo multiple-scattering in nuclei. These results show that angular correlation studies can open a new way to elucidate how hadrons form and interact inside nuclei, Comment: 6 pages, 4 figures

Published
2022

2. Measurement of deeply virtual Compton scattering off He4 with the CEBAF Large Acceptance Spectrometer at Jefferson Lab

Author

T. A. Forest, D. P. Watts, H. Egiyan, F. Sabatié, D. Bulumulla, A. Filippi, Aditya R. Khanal, M. Khandaker, G. Rosner, Andrea Bianconi, D. Payette, Jo H. S., Y. Ghandilyan, H. Voskanyan, W. Kim, R. A. Schumacher, P. Lenisa, S. Bültmann, W. J. Briscoe, E. Pasyuk, Maxime Defurne, N. Markov, B. Torayev, R. Dupre, D. G. Ireland, Carlos A. Salgado, V. Crede, B. A. Clary, M. Contalbrigo, K. Livingston, M. Battaglieri, M. J. Amaryan, B. Yale, G. Costantini, S. Stepanyan, V. P. Kubarovsky, A. Kim, R. De Vita, J. Rowley, Whitney Armstrong, Simonetta Liuti, Krishna Neupane, J. Poudel, O. Pogorelko, K. Wei, S. Fegan, P. Eugenio, Dustin Keller, R. Paremuzyan, G. Khachatryan, Volker D. Burkert, M. L. Kabir, H. Atac, T. B. Hayward, Paolo Rossi, A. S. Biselli, R. Wishart, A. Celentano, R. W. Gothe, M. Guidal, K. Hafidi, V. Mokeev, Larry Weinstein, Gerard Gilfoyle, L. Venturelli, Michael Paolone, E. L. Isupov, D. Sokhan, M. Ehrhart, M. Caudron, M. Osipenko, S. Boiarinov, I. J. D. MacGregor, F. Bossu, A. Vossen, G. Ciullo, Fatiha Benmokhtar, Y. Prok, D. S. Carman, M. Holtrop, O. Soto, N. A. Baltzell, Nikos Sparveris, X. Wei, H. Hakobyan, M. H. Wood, E. Voutier, J. Ritman, S. Diehl, N. Dashyan, A. El Alaoui, B. McKinnon, Luciano Pappalardo, M. Bondì, K. A. Griffioen, Yordanka Ilieva, C. Ayerbe Gayoso, Nicholas Zachariou, J. C. Carvajal, Y. Perrin, V. Chesnokov, L. Barion, U. Shrestha, M. Mirazita, L. Lanza, K. Hicks, W. Phelps, V. Mascagna, D. Marchand, S. Niccolai, Alessandro Rizzo, Alexander Schmidt, I. Bedlinskiy, M. Ripani, P. Chatagnon, M. Ungaro, K. Joo, V. Sergeyeva, J. Zhang, F. X. Girod, N. Tyler, C. Djalali, T. Chetry, S. Strauch, L. Elouadrhiri, S. Joosten, I. I. Strakovsky, A. Deur, D. G. Jenkins, A. Hobart, M. Leali, T. R. O'Connell, N. Pivnyuk, A. D'Angelo, L. El Fassi, S. E. Kuhn, M. Hattawy, P. L. Cole, Martin K. Mayer, A. Kripko, and Y. G. Sharabian

Subjects
Nuclear physics, Physics, Spectrometer, 010308 nuclear & particles physics, 0103 physical sciences, Compton scattering, Perturbative QCD, 010306 general physics, 01 natural sciences
Published
2021

3. Measurement of the beam spin asymmetry of e→p→e′p′η in the deep-inelastic regime with CLAS

Author

M. Guidal, C. Djalali, J. A. Tan, A. I. Ostrovidov, K. Park, Z.W. Zhao, G. D. Smith, M. Holtrop, M. Hattawy, D. G. Ireland, Iu. Skorodumina, Volker D. Burkert, K. A. Griffioen, A. S. Biselli, Maxime Defurne, V. Mokeev, D. Marchand, X. Wei, M. Bashkanov, S. Adhikari, V. Crede, Rong Wang, B. McKinnon, P. Lenisa, L. Lanza, Taya Chetry, R. A. Montgomery, C. A. Meyer, N. A. Baltzell, Y. G. Sharabian, P. Chatagnon, M. Ehrhart, W. Kim, D. G. Jenkins, A. Kim, Y. Prok, M. Mirazita, Z. E. Meziani, A. Celentano, R. W. Gothe, R. De Vita, G. Niculescu, Sergey Kuleshov, F. Sabatié, N. Markov, F. X. Girod, V. Batourine, M. Ungaro, N. Dashyan, M. Khachatryan, V. P. Kubarovsky, H. S. Jo, R. Paremuzyan, K. Livingston, O. Pogorelko, L. Barion, G. Rosner, Nicholas M. Harrison, Gerard Gilfoyle, Friedrich Klein, M. Battaglieri, H. Avakian, K. Joo, S. Strauch, H. Hakobyan, D. Sokhan, I. Bedlinskiy, H. Voskanyan, Y. Ghandilyan, Laura Clark, B. S. Ishkhanov, H. Egiyan, Jie Zhang, S. Diehl, C. Salgado, M. Osipenko, K. Hicks, B. Zhao, G. Khachatryan, P. Nadel-Turonski, G. Ciullo, J. P. Ball, S. E. Kuhn, D. S. Carman, Dustin Keller, D. Heddle, Nikos Sparveris, E. De Sanctis, R. A. Schumacher, G. Angelini, P. Eugenio, S. Johnston, L. Guo, Alessandro Rizzo, S. Niccolai, Michael Wood, P. Rossi, C. Munoz Camacho, K. Hafidi, W. J. Briscoe, M. L. Kabir, E. Golovatch, R. Dupre, T. A. Forest, S. Stepanyan, A. Filippi, Avraham Klein, E. L. Isupov, G. Gavalian, I. J. D. MacGregor, M. Contalbrigo, M. Khandaker, I. I. Strakovsky, A. Deur, M. Ripani, S. Boiarinov, M. Taiuti, W. K. Brooks, B. A. Clary, Z. Akbar, Michael Paolone, J. W. Price, A. D'Angelo, D. Protopopescu, E. Voutier, L. El Fassi, A. El Alaoui, Y. Ilieva, Nicholas Zachariou, and P. L. Cole

Subjects
Physics, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Scattering, media_common.quotation_subject, Hadron, Virtual particle, Parton, 01 natural sciences, Asymmetry, Nuclear physics, Pseudoscalar, 0103 physical sciences, Nuclear Experiment, 010306 general physics, Spin-½, media_common, Lepton
Abstract

The beam spin asymmetry of the exclusive pseudoscalar channel e → p → e ′ p ′ η was measured for the first time in the deep-inelastic regime ( W > 2 GeV / c 2 and Q 2 > 1 GeV 2 / c 2 ) using a longitudinally polarized 5.78 GeV electron beam at Jefferson Lab with the CEBAF Large Acceptance Spectrometer. The data were accumulated in 144 four-dimensional bins of Q 2 , x B , − t and ϕ over a wide kinematic range, where ϕ is the azimuthal angle between the lepton and hadron scattering planes, The measured azimuthal dependence with large amplitudes of the sin ⁡ ϕ moments is a clear indication of a substantial contribution to the polarized cross-section from transversely polarized virtual photons. In the framework of generalized parton distributions (GPDs) this contribution is expressed via longitudinal-transverse interference between chiral-even and chiral-odd GPDs. The experimental results are compared to the existing theoretical models demonstrating the sensitivity to the product of chiral-odd and chiral-even GPDs and provide new constraints to the existing GPD parameterizations.

Published
2019

4. Observation of Beam Spin Asymmetries in the Process ep→e′π+π−X with CLAS12

Author

G. Niculescu, D. Bulumulla, G. Ciullo, Aditya R. Khanal, A. El Alaoui, S. Niccolai, E. L. Isupov, D. S. Carman, F. X. Girod, Nikos Sparveris, K. A. Griffioen, D. G. Ireland, V. I. Mokeev, M. Contalbrigo, V. Crede, Nicholas Zachariou, J. C. Carvajal, Sung-Sik Lee, X. Wei, S. Boiarinov, Andrea Bianconi, P. Lenisa, C. Dilks, Fatiha Benmokhtar, O. Soto, T. B. Hayward, M. Osipenko, R. Paremuzyan, L. Marsicano, Maxime Defurne, B. A. Clary, Latifa Elouadrhiri, A. Movsisyan, N. Tyler, N. Markov, P. L. Cole, N. Dashyan, K. Hicks, I. J. D. MacGregor, S. Strauch, D. I. Glazier, V. P. Kubarovsky, Michael Paolone, Krishna Neupane, H. Hakobyan, F. Bossu, R. Tyson, J. Ritman, Eugene Pasyuk, R. De Vita, D. Marchand, H. S. Jo, H. Avakian, Eric Voutier, L. Lanza, S. Diehl, C. Salgado, A. A. Golubenko, H. Atac, H. Voskanyan, G. Costantini, W. J. Briscoe, L. Barion, S. E. Kuhn, M. Hattawy, A. Vossen, M. Guidal, A. D'Angelo, Dustin Keller, M Ehrhart, P. Naidoo, T. Chetry, D. P. Watts, P. Chatagnon, Y. Prok, U. Shrestha, Michael Wood, F. Sabatié, M. Holtrop, Chaden Djalali, L. El Fassi, V. Mascagna, G. Gavalian, K. Hafidi, A. Filippi, B. A. Raue, Luciano Pappalardo, C. Ayerbe Gayoso, I. Bedlinskiy, Michael Dugger, W. Phelps, G. Angelini, P. Rossi, K. Wei, S. Joosten, S. Fegan, M. Leali, A. Celentano, R. W. Gothe, P. Nadel-Turonski, M. Khachatryan, N. A. Baltzell, K. Livingston, Alessandro Rizzo, Axel Schmidt, T. R. O'Connell, William Brooks, I. I. Strakovsky, F. Hauenstein, A. Kim, L. Venturelli, Jie Zhang, Y. Gotra, Z. E. Meziani, A. Deur, B. Yale, E.P. Segarra, S. Nanda, A. Kripko, T. A. Forest, S. Stepanyan, Y. G. Sharabian, M. Ripani, R. Dupré, M. Bondì, M. Battaglieri, O. Pogorelko, J. Rowley, Volker D. Burkert, A. S. Biselli, A. Hobart, S. Adhikari, B. McKinnon, M. Mirazita, Gerard Gilfoyle, D. Sokhan, M. Arratia, Hovanes Egiyan, C. Munoz Camacho, M. Ungaro, K. Joo, A. Thornton, and W. Kim

Subjects
Quark, Physics, Spectrometer, Proton, Nuclear Theory, General Physics and Astronomy, Deep inelastic scattering, 01 natural sciences, Gluon, Nuclear physics, 0103 physical sciences, Cathode ray, Physics::Accelerator Physics, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, Beam (structure), Spin-½
Abstract

The observation of beam spin asymmetries in two-pion production in semi-inclusive deep inelastic scattering off an unpolarized proton target is reported for the first time. The data presented here were taken in the fall of 2018 with the CLAS12 spectrometer using a 10.6 GeV longitudinally spin-polarized electron beam delivered by CEBAF at JLab. The measured asymmetries provide the first observation of a signal that can be used to extract the PDF $e(x)$ in a collinear framework and the helicity-dependent two-pion fragmentation function $G_1^\perp$.

Published
2021

5. Photoproduction of the f2(1270) Meson Using the CLAS Detector

Author

V. Mokeev, P. Eugenio, Vincent Mathieu, D. Heddle, R. A. Schumacher, M. Battaglieri, K. A. Griffioen, R. Paremuzyan, Laura Clark, L. Marsicano, L. Lanza, M. J. Amaryan, M Carver, G. Angelini, D. P. Watts, Gerard Gilfoyle, M. Osipenko, N. Gevorgyan, P. Lenisa, M. Contalbrigo, H. Egiyan, K. Livingston, R. Tyson, D. Sokhan, S. Stepanyan, I. J. D. MacGregor, F. X. Girod, S. Adhikari, Dustin Keller, F. Sabatié, B. McKinnon, G. Niculescu, G. Rosner, B. A. Clary, D. G. Ireland, V. Crede, D. Bulumulla, William Brooks, E. Munevar, Jie Zhang, T. B. Hayward, K. Hafidi, A. Filippi, W. Phelps, Z. E. Meziani, B. Yale, Aditya R. Khanal, L. Venturelli, M. Ehrhart, M. Khandaker, E. L. Isupov, Friedrich Klein, Alessandro Rizzo, A. Kim, Michael Paolone, S. Boiarinov, Andrea Bianconi, G. Ciullo, A. Pilloni, C. W. Kim, A. Celentano, R. W. Gothe, Y. Prok, C. E. Hyde, I. Bedlinskiy, A. El Alaoui, N. A. Baltzell, F. Bossu, T. Chetry, D. S. Carman, Nicholas Zachariou, H. S. Jo, U. Shrestha, J. C. Carvajal, H. Voskanyan, Z. W. Zhao, Fatiha Benmokhtar, Nikos Sparveris, X. Wei, W. J. Briscoe, O. Soto, V. Mascagna, Maxime Defurne, M. Holtrop, S. Joosten, S. Niccolai, D. Protopopescu, E. Voutier, Luciano Pappalardo, A. Movsisyan, R. De Vita, H. Hakobyan, O. Pogorelko, S. Strauch, J. Ritman, J. Rowley, A. I. Ostrovidov, P. Chatagnon, K. Wei, S. Diehl, C. Salgado, S. Fegan, H. Atac, Volker D. Burkert, C. Munoz Camacho, Eugene Pasyuk, A. S. Biselli, G. Gavalian, V. P. Kubarovsky, Krishna Neupane, M. Ripani, M. Hattawy, K. Hicks, N. Dashyan, Michael Dugger, Yordanka Ilieva, L. Barion, Barry Ritchie, R. Dupre, D. Marchand, M. Ungaro, G. V. Fedotov, Q. Huang, K. P. Adhikari, K. Joo, D. G. Jenkins, M. Leali, Axel Schmidt, I. I. Strakovsky, P. Nadel-Turonski, A. Deur, Mark W. Bondi, M. E. McCracken, N. Tyler, C. Djalali, A. D'Angelo, L. El Fassi, A. Kripko, Y. G. Sharabian, and P. L. Cole

Subjects
Quark, Physics, Spectrometer, Meson, High Energy Physics::Lattice, Nuclear Theory, Quark model, Detector, General Physics and Astronomy, Quantum number, 01 natural sciences, 7. Clean energy, Resonance (particle physics), Nuclear physics, Pion, 0103 physical sciences, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics
Abstract

The quark structure of the f2(1270) meson has, for many years, been assumed to be a pure quark-antiquark (qq¯) resonance with quantum numbers JPC=2++. Recently, it was proposed that the f2(1270) is a molecular state made from the attractive interaction of two ρ mesons. Such a state would be expected to decay strongly to final states with charged pions due to the dominant decay ρ→π+π-, whereas decay to two neutral pions would likely be suppressed. Here, we measure for the first time the reaction γp→π0π0p, using the CEBAF Large Acceptance Spectrometer detector at Jefferson Lab for incident beam energies between 3.6 and 5.4 GeV. Differential cross sections, dσ/dt, for f2(1270) photoproduction are extracted with good precision due to low backgrounds and are compared to theoretical calculations.

Published
2021

6. Beam Spin Asymmetry in Semi-Inclusive Electroproduction of Hadron Pairs

Author

K. Park, V. P. Kubarovsky, Krishna Neupane, C. W. Kim, H. Avakian, H. Voskanyan, W. J. Briscoe, Dustin Keller, P. Eugenio, Michael Wood, K. Hafidi, G. Gavalian, L. Marsicano, A Hobart, V. Mokeev, F. X. Girod, R. A. Schumacher, M. Battaglieri, I. I. Strakovsky, R. W. Gothe, T. Chetry, M. J. Amaryan, F. Sabatié, K. Wei, S. Fegan, N. Markov, L. Guo, Alessandro Rizzo, K. A. Griffioen, Fatiha Benmokhtar, Gerard Gilfoyle, R. Paremuzyan, E. L. Isupov, A. Deur, S. Pisano, V. Crede, Ross Milner, O. Soto, P. Lenisa, M. Contalbrigo, C. Dilks, L. Lanza, M. Ungaro, T. A. Forest, C. Mullen, W. K. Brooks, M. Guidal, Z. W. Zhao, S. Stepanyan, N. A. Baltzell, M. Holtrop, T. B. Hayward, Friedrich Klein, Andrea Celentano, O. Pogorelko, J. Poudel, A. Filippi, Brian Raue, K. Hicks, K. Joo, D. Marchand, M. Osipenko, Luciano Pappalardo, K. L. Giovanetti, Hovanes Egiyan, M. Ripani, C. Munoz Camacho, A. D'Angelo, B. Yale, S. Adhikari, L. Venturelli, B. McKinnon, M. Ehrhart, D. G. Ireland, Tim O'Connell, I. Bedlinskiy, D. I. Glazier, W. Phelps, D. G. Jenkins, N. Tyler, M. Leali, L. El Fassi, C. Djalali, Volker D. Burkert, W. Kim, T. Mineeva, D. Heddle, R. De Vita, G. Ciullo, V. Mascagna, H. S. Jo, A. S. Biselli, M. Mirazita, D. Bulumulla, Y. Prok, D. S. Carman, G. Niculescu, B. S. Ishkhanov, E. Pasyuk, Aditya R. Khanal, X. Wei, R. G. Fersch, Andrea Bianconi, H. Atac, P. L. Cole, N. Dashyan, G. Angelini, P. Chatagnon, B. A. Clary, P. Rossi, M. Defurne, Michael Paolone, L. Barion, Axel Schmidt, Aurore Courtoy, K. Livingston, M. Khandaker, Jie Zhang, I. J. D. MacGregor, E. Golovatch, R. Dupre, Y. Ghandilyan, Q. Huang, E. Voutier, A. Vossen, A. El Alaoui, Y. Ilieva, Nicholas Zachariou, J. C. Carvajal, S. Strauch, D. P. Watts, F. Bossu, Nikolaos Sparveris, Dinko Pocanic, S. E. Kuhn, M. Hattawy, Y. G. Sharabian, S. Boiarinov, H. Hakobyan, J. Ritman, S. Diehl, C. Salgado, U. Shrestha, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and CLAS

Subjects
High Energy Physics::Lattice, Nuclear Theory, Hadron, parton: distribution function, General Physics and Astronomy, Parton, 01 natural sciences, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), Economica, higher-twist, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Nuclear Experiment (nucl-ex), electron: beam, Nuclear Experiment, dimension: 1, Physics, Quantum chromodynamics, deep inelastic scattering: semi-inclusive reaction, Settore FIS/04, nucleon, kinematics, Quarks and Gluons, helicity distributions, quark: valence, Nucleon, Jefferson Lab, Quark, Particle physics, polarization: longitudinal, FOS: Physical sciences, Socio-culturale, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Transversity Distributions, hadron: electroproduction, hadron: pair production, Pion, CLAS, Hadron Physics, quantum chromodynamics, 0103 physical sciences, ddc:530, 010306 general physics, High Energy Physics::Phenomenology, Ambientale, Deep inelastic scattering, spin: asymmetry: measured, Distribution function, Elementary Particles and Fields, QCD Dynamics, High Energy Physics::Experiment, pi: pair production, experimental results
Abstract

Physical review letters 126(6), 062002 (2021). doi:10.1103/PhysRevLett.126.062002, Published by APS, College Park, Md.

Published
2021

7. Measurement of deeply virtual Compton scattering off He 4 with the CEBAF Large Acceptance Spectrometer at Jefferson Lab

Author

R. Dupré, M. Hattawy, N. A. Baltzell, S. Bültmann, R. De Vita, A. El Alaoui, L. El Fassi, H. Egiyan, F. X. Girod, M. Guidal, K. Hafidi, D. Jenkins, S. Liuti, Y. Perrin, S. Stepanyan, B. Torayev, E. Voutier, M. J. Amaryan, W. R. Armstrong, H. Atac, C. Ayerbe Gayoso, L. Barion, M. Battaglieri, I. Bedlinskiy, F. Benmokhtar, A. Bianconi, A. S. Biselli, M. Bondi, F. Bossù, S. Boiarinov, W. J. Brisco

Published
2021
Full Text
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8. Exclusive π0p electroproduction off protons in the resonance region at photon virtualities 0.4GeV2≤Q2≤1GeV2

Author

P. Eugenio, M. Taiuti, Carlos A. Salgado, L. C. Smith, I. I. Strakovsky, B. S. Ishkhanov, R. Dupre, M. Battaglieri, Aditya R. Khanal, A. Deur, R. A. Schumacher, M. Contalbrigo, Michael Paolone, F. Bossu, C. Evans, Maxime Defurne, N. Tyler, C. Djalali, J. A. Tan, K. A. Griffioen, Pawel Nadel-Turonski, Fatiha Benmokhtar, O. Soto, R. De Vita, M. Ungaro, S. Niccolai, L. Lanza, A. D'Angelo, A. Kim, Alessandro Rizzo, T. Mineeva, S. Stepanyan, W. Kim, U. Shrestha, V. Crede, L. El Fassi, T. B. Hayward, H. Atac, R. Paremuzyan, P. Stoler, K. Joo, D. G. Jenkins, M. Leali, K. Hicks, G. Ciullo, William Brooks, N. Markov, M. Guidal, G. Niculescu, Y. Prok, L. Venturelli, W. Phelps, E. De Sanctis, V. Mascagna, I. Bedlinskiy, E. Golovatch, D. S. Carman, A. Celentano, R. W. Gothe, E. L. Isupov, M. Holtrop, Nikos Sparveris, C. W. Kim, Luciano Pappalardo, X. Wei, F. X. Girod, S. Boiarinov, G. Angelini, H. Avakian, J. W. Price, P. L. Cole, G. Rosner, N. A. Baltzell, T. Chetry, J. Rowley, K. Park, D. Sokhan, Y. Ghandilyan, F. Sabatié, Y. G. Sharabian, H. Hakobyan, H. S. Jo, E. Voutier, S. Diehl, D. G. Ireland, I. J. D. MacGregor, N. Dashyan, Volker D. Burkert, A. S. Biselli, S. Strauch, S. Adhikari, M. H. Wood, M. Osipenko, P. Chatagnon, B. McKinnon, Yordanka Ilieva, V. Mokeev, M. Mirazita, Rong Wang, M. Ehrhart, L. Barion, M. Hattawy, H. Voskanyan, S. K. Nanda, M. Ripani, M. Khachatryan, W. J. Briscoe, D. Marchand, E. Pasyuk, V. P. Kubarovsky, D. Riser, A. El Alaoui, C. Ayerbe Gayoso, Nicholas Zachariou, J. C. Carvajal, O. Pogorelko, D. Protopopescu, Frank Klein, Dustin Keller, K. Livingston, K. Hafidi, M. J. Amaryan, A. Filippi, and M. Khandaker

Subjects
Physics, Range (particle radiation), Photon, Proton, 010308 nuclear & particles physics, Resonance, 01 natural sciences, Nuclear physics, Cross section (physics), Isospin, 0103 physical sciences, Invariant mass, 010306 general physics, Legendre polynomials
Abstract

The exclusive electroproduction process ep→e′p′π0 was measured in the range of photon virtualities Q2=0.4–1.0GeV2 and the invariant mass range of the pπ0 system of W=1.1–1.8 GeV. These kinematics are covered in exclusive π0 electroproduction off the proton with nearly complete angular coverage in the pπ0 center-of-mass system and with high statistical accuracy. Nearly 36 000 cross-section points were measured, and the structure functions σT+eσL,σLT, and σTT, were extracted via fitting the ϕπ0 dependence of the cross section. A Legendre polynomial expansion analysis demonstrates the sensitivity of our data to high-lying N* and Δ* resonances with M>1.6 GeV. As part of a broad effort to determine the electrocouplings of the N* and Δ* resonances using both single- and double-pion electroproduction, this dataset is crucial for the reliable extraction of the high-lying resonance electrocouplings from the combined isospin analysis of the Nπ and π+π−p channels.

Published
2020

9. The CLAS12 Spectrometer at Jefferson Laboratory

Author

C. W. Kim, H. Avakian, D. Protopopescu, D. Heddle, M. Contalbrigo, M. L. Kabir, H. Voskanyan, E. Voutier, T. Chetry, M. Zarecky, J. Poudel, I. Illari, B. A. Clary, M. Osipenko, D. Insley, D. P. Watts, I. Bedlinskiy, Michael Paolone, V. Sergeyeva, D. Kashy, M. Khachatryan, F. Hauenstein, V. Mascagna, Nikolaos Sparveris, F. Bossu, D. Marchand, W. Kim, G. Niculescu, P. Bonneau, G. Charles, P. Hemler, Ruben J. Fair, P. Moran, Dustin Keller, C. Ayerbe Gayoso, Nicholas Zachariou, M. Ungaro, C. Munoz Camacho, M. J. Amaryan, G. Rosner, I. J. D. MacGregor, T. A. Forest, V. Lucherini, S. E. Kuhn, Y. Prok, M. Hattawy, S. Stepanyan, Michael Wood, K. Hafidi, M. D. Mestayer, S. Lee, M. Wiseman, F. Sabatié, R. Paremuzyan, N. Dashyan, A. Deur, K. Hicks, K. Joo, E. L. Isupov, N. A. Baltzell, R. W. Gothe, S. Christo, L. C. Smith, B. S. Ishkhanov, Latifa Elouadrhiri, V. Baturin, Nicholas M. Harrison, Gerard Gilfoyle, M. McMullen, G. E. Dodge, H. S. Jo, R. Johnston, A. Yegneswaran, K. Livingston, A. Lung, P. Stoler, M. Guidal, D. Sokhan, K. Price, Aditya R. Khanal, K. P. Adhikari, Jie Zhang, K. Bruhwel, S. Adhikari, S. Boyarinov, B. McKinnon, M. Ehrhart, M. Leali, Z. W. Zhao, S. Joosten, B. J. Roy, V. P. Kubarovsky, J. Newton, P. Chatagnon, G. V. Fedotov, D. Tilles, M.A. Antonioli, Renuka Rajput-Ghoshal, G. D. Smith, M. Holtrop, C. Cuevas, V. Gyurjyan, Probir K. Ghoshal, Yordanka Ilieva, H. Hakobyan, Alexander Schmidt, Luciano Pappalardo, Andrea Bianconi, W. J. Briscoe, M. Turisini, M. Mirazita, D. I. Glazier, M. Garçon, M. Ripani, F. X. Girod, A. Filippi, K. L. Giovanetti, R. Miller, J. Ritman, S. Diehl, R. De Vita, C. D. Keith, Y. G. Sharabian, M. Lowry, M. Defurne, E. Pasyuk, P. Naidoo, J. Hogan, N. Markov, Or Hen, C. Salgado, M. Taylor, G. Young, S. Strauch, Larry Weinstein, H. Atac, Chaden Djalali, A. Hobart, A. Kim, Z. E. Meziani, S. Schadmand, U. Shrestha, T. Ewing, T. Mineeva, O. Pogorelko, S. Nanda, L. Barion, G. Angelini, J. Rowley, P. Rossi, M. Leffel, William Brooks, I. Mandjavidze, L. Venturelli, Iu. Skorodumina, Y. Gotra, C. Mealer, J. W. Price, S. Aune, C. Wiggins, D. G. Ireland, G. Gavalian, G. Jacobs, V. Crede, Volker D. Burkert, A. S. Biselli, O. Pastor, Victor Mokeev, E.P. Segarra, Ross Milner, N. Tyler, J. A. Tan, E. Golovatch, R. Dupre, W. Phelps, Andrea Celentano, S. Procureur, M. Cook, G. Ciullo, M. Battaglieri, D. S. Carman, B. Raydo, A. Rizzo, X. Wei, R. Cruz-Torres, S. Niccolai, K. A. Griffioen, B. Eng, A. Movsisyan, P. L. Cole, L. Lanza, G. Christiaens, A. D'Angelo, T. Kageya, L. El Fassi, P. Lenisa, V. Ziegler, C. Hanretty, D. Anderson, T. B. Hayward, Brian Raue, Fatiha Benmokhtar, O. Soto, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics::Instrumentation and Detectors, data acquisition, magnet: solenoid, superconductivity: torus, Solenoid, 01 natural sciences, Particle identification, Luminosity, momentum resolution, electron: beam, Nuclear Experiment, Instrumentation, QC, Physics, Luminosity (scattering theory), Settore FIS/04, Detector, Magnetic spectrometer, magnet: torus, performance, Nuclear and High Energy Physics, Meson, vertex detector, nucleon: interaction, CLAS12, Electromagnetic physics, Large acceptance, Socio-culturale, fabrication, beam: energy, Nuclear physics, PE2_1, CLAS, 0103 physical sciences, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], 010306 general physics, PE2_3, scintillation counter, Cherenkov radiation, detector: design, activity report, Spectrometer, 010308 nuclear & particles physics, nucleus, CLAS12, Electromagnetic physics, Large acceptance, Luminosity, Magnetic spectrometer, magnet: superconductivity, magnetic spectrometer, electromagnetic physics, large acceptance, luminosity, neutral particle, Automatic Keywords, calorimeter: electromagnetic, Cherenkov counter, spectrometer, particle identification, Beam (structure)
Abstract

International audience; The CEBAF Large Acceptance Spectrometer for operation at 12 GeV beam energy (CLAS12) in Hall B at Jefferson Laboratory is used to study electro-induced nuclear and hadronic reactions. This spectrometer provides efficient detection of charged and neutral particles over a large fraction of the full solid angle. CLAS12 has been part of the energy-doubling project of Jefferson Lab’s Continuous Electron Beam Accelerator Facility, funded by the United States Department of Energy. An international collaboration of 48 institutions contributed to the design and construction of detector hardware, developed the software packages for the simulation of complex event patterns, and commissioned the detector systems. CLAS12 is based on a dual-magnet system with a superconducting torus magnet that provides a largely azimuthal field distribution that covers the forward polar angle range up to 35 ∘ , and a solenoid magnet and detector covering the polar angles from 35° to 125° with full azimuthal coverage. Trajectory reconstruction in the forward direction using drift chambers and in the central direction using a vertex tracker results in momentum resolutions of < 1% and < 3%, respectively. Cherenkov counters, time-of-flight scintillators, and electromagnetic calorimeters provide good particle identification. Fast triggering and high data-acquisition rates allow operation at a luminosity of 1035 cm −2 s −1 . These capabilities are being used in a broad program to study the structure and interactions of nucleons, nuclei, and mesons, using polarized and unpolarized electron beams and targets for beam energies up to 11 GeV. This paper gives a general description of the design, construction, and performance of CLAS12.

Published
2020

10. The CLAS12 superconducting magnets

Author

F. Nobrega, Probir K. Ghoshal, N. A. Baltzell, T. Lemon, Mark Wiseman, B. Eng, V.V. Kashikhin, D. Insley, Onish Kumar, L. Elementi, P. Campero-Rojas, Robert Legg, G.V. Velev, Ramakrishna Bachimanchi, Volker D. Burkert, M. Lester, A. Lung, R. Miller, S. Krave, V. Lagerquist, N. Sandoval, C. H. Rode, Cesar Luongo, D. Kashy, Glenn Young, M. D. Mestayer, G.H. Biallas, O. Pastor, J. Newton, Latifa Elouadrhiri, S. Philip, D. Tilles, V. Rao Ganni, Renuka Rajput-Ghoshal, Ruben J. Fair, C. Wilson, K. Tremblay, Joseph R. Matalevich, J. Hogan, M. Laney, W. Moore, S. L. Spiegel, and ITER organization (ITER)

Subjects
solenoid, Nuclear and High Energy Physics, magnet: design, Physics::Instrumentation and Detectors, [PHYS.PHYS.PHYS-ACC-PH]Physics [physics]/Physics [physics]/Accelerator Physics [physics.acc-ph], Mechanical engineering, Solenoid, Superconducting magnet, fabrication, 01 natural sciences, law.invention, chemistry.chemical_compound, law, CLAS, Superconducting, 0103 physical sciences, Shielded cable, Niobium-tin, 010306 general physics, Instrumentation, 010302 applied physics, Physics, Toroid, Torus, magnet: superconductivity, Quench, chemistry, Mapping, Electromagnetic coil, Magnet, Magnets, Physics::Accelerator Physics, niobium: tin
Abstract

International audience; As part of the Jefferson Lab 12 GeV upgrade, the Hall B CLAS12 system requires two superconducting iron-free magnets — a torus and a solenoid. The physics requirements to maximize space for the detectors guided engineers toward particular coil designs for each of the magnets which, in turn, led to the choice of using conduction cooling. The torus consists of 6 trapezoidal NbTi coils connected in series with an operating current of 3770 A. The solenoid is an actively shielded 5 T magnet consisting of 5 NbTi coils connected in series operating at 2416 A. Within the hall, the two magnets are located in close proximity to each other and are completely covered both inside and outside by particle detectors. Stringent size limitations were imposed for both magnets and introduced particular design and fabrication challenges. This paper describes the design, construction, installation, commissioning, and operation of the two magnets.

Published
2020

11. The CLAS12 software framework and event reconstruction

Author

Maxime Defurne, D. I. Glazier, R. De Vita, F. Bossu, D. S. Carman, A. Hobart, M. D. Mestayer, Y. Gotra, M. Ungaro, N. A. Baltzell, P. Chatagnon, M. Contalbrigo, S. Joosten, W. Phelps, A. Kim, S. Niccolai, V. Gyurjyan, Gagik Gavalian, V. Ziegler, D. Heddle, Nicholas M. Harrison, Gerard Gilfoyle, D. Sokhan, J. Newton, N. Markov, S. Mancilla, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Scheme (programming language), Nuclear and High Energy Physics, Hadronic physics, computer.software_genre, 01 natural sciences, Software, 0103 physical sciences, Electron scattering, [INFO]Computer Science [cs], [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], 010306 general physics, Nuclear Experiment, Instrumentation, computer.programming_language, Event reconstruction, Physics, Data processing, Spectrometer, 010308 nuclear & particles physics, business.industry, Detector, Software framework, Identification (information), Computer engineering, Event reconstruction software, business, computer
Abstract

International audience; We describe offline event reconstruction for the CEBAF Large Acceptance Spectrometer at 12 GeV (CLAS12), including an overview of the offline reconstruction framework and software tools, a description of the algorithms developed for the individual detector subsystems, and the overall approach for charged and neutral particle identification. We also present the scheme for data processing and the code management procedures.

Published
2020

12. The CLAS12 Silicon Vertex Tracker

Author

C. Cuevas, T. Ewing, M. Merkin, S. Mandal, B. Marzolf, B. Eng, Latifa Elouadrhiri, W. Teachey, Maxime Defurne, Gerard Gilfoyle, M.A. Antonioli, P. Bonneau, L. Zana, Ross J. Tucker, Y. Gotra, M. Ungaro, M. Leffel, V. Ziegler, S. Boyarinov, R. Miller, B. Raydo, G. Derylo, M. McMullen, S. Christo, A. Yegneswaran, N. A. Baltzell, and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
Nuclear and High Energy Physics, Vertex (computer graphics), 020209 energy, vertex detector, 02 engineering and technology, STRIPS, Tracking (particle physics), 01 natural sciences, Microstrip, law.invention, law, CLAS, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, Fermilab, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Instrumentation, detector: design, Physics, Spectrometer, 010308 nuclear & particles physics, business.industry, Electrical engineering, integrated circuit, Upgrade, Vertex tracker, electronics: readout, semiconductor detector: microstrip, Silicon detectors, upgrade, Photonics, business, CLAS12, performance
Abstract

International audience; For the 12 GeV upgrade of Jefferson Laboratory, a Silicon Vertex Tracker (SVT) has been designed for the CLAS12 spectrometer using single-sided microstrip sensors fabricated by Hamamatsu Photonics. The sensors have a graded angle design to minimize dead areas and a readout pitch of 156μm , with intermediate strips. Each double-sided SVT module hosts three daisy-chained sensors on each side with a full strip length of 33 cm. There are 512 channels per module, read out by four Fermilab Silicon Strip Readout (FSSR2) chips, featuring data-driven architecture, mounted on a rigid–flex hybrid board. The modules are assembled in a barrel configuration using a unique cantilevered geometry to minimize the amount of material in the tracking volume. This paper is focused on the design, qualification of the performance, and experience in operating and commissioning the tracker during the first year of the data taking.

Published
2020

13. Semi-inclusive π0 target and beam-target asymmetries from 6 GeV electron scattering with CLAS

Author

P. Lenisa, W. Kim, R. Dupre, M. Battaglieri, G. Niculescu, G. Rosner, K. Livingston, M. Hattawy, Friedrich Klein, Y. Ghandilyan, A. Filippi, X. Wei, Brian Raue, M. Khandaker, M. J. Amaryan, V. I. Mokeev, D. Heddle, K. L. Giovanetti, Larry Weinstein, G. Hollis, R. A. Schumacher, Jie Zhang, K. A. Griffioen, Dustin Keller, C. Hanretty, N. Guler, G. Khachatryan, A. Celentano, R. W. Gothe, D. P. Watts, P. Nadel-Turonski, Michael Wood, Taya Chetry, W. J. Briscoe, H. Egiyan, M. Ungaro, Laura Clark, L. Lanza, S. Bültmann, M. E. McCracken, Sergey Kuleshov, K. P. Adhikari, T. A. Forest, C. Carlin, H. Avakian, F. X. Girod, S. Pisano, B. S. Ishkhanov, Sylvester Joosten, P. Eugenio, F. Cao, P. Bosted, P. Rossi, S. Strauch, D. Adikaram, E. De Sanctis, M. Guidal, M. Taiuti, J. Brock, C. Munoz Camacho, K. Joo, H. Hakobyan, D. Protopopescu, G. D. Smith, M. Holtrop, W. Phelps, V. Crede, C. Salgado, D. I. Sober, M. Garçon, J. Pierce, E. Voutier, S. Adhikari, B. McKinnon, Avraham Klein, R. A. Montgomery, C. Djalali, H. Voskanyan, Maxime Defurne, I. Bedlinskiy, L. Colaneri, O. Cortes, M. Mirazita, E. Phelps, H. Y. Lu, E. L. Isupov, E. Pasyuk, V. Batourine, R. De Vita, A. El Alaoui, S. Boiarinov, Nicholas Zachariou, A. D'Angelo, R. Paremuzyan, S. Anefalos Pereira, Nicholas M. Harrison, Gerard Gilfoyle, A. Kim, D. Sokhan, N. Markov, N. A. Baltzell, L. El Fassi, J. W. Price, I. Niculescu, V. P. Kubarovsky, Z. W. Zhao, K. Hicks, D. Riser, C. D. Keith, A. I. Ostrovidov, L. Guo, Alessandro Rizzo, O. Pogorelko, S. M. Hughes, K. Park, G. Ddoge, D. G. Ireland, I. Stankovic, T. Mineeva, H. Jiang, R. G. Fersch, Volker D. Burkert, A. S. Biselli, William Brooks, P. L. Cole, S. Koirala, A. Fradi, M. Osipenko, M. Contalbrigo, D. G. Jenkins, Iu. Skorodumina, Z. Akbar, G. Charles, A. Simonyan, F. Sabatié, N. K. Walford, S. S. Jawalkar, I. J. D. MacGregor, W. Gohn, E. Golovatch, A. Deur, L. A. Net, Latifa Elouadrhiri, C. A. Meyer, Y. G. Sharabian, G. V. Fedotov, N. Dashyan, S. E. Kuhn, Yordanka Ilieva, J. A. Fleming, Martin K. Mayer, M. Khachatryan, S. Fegan, C. Gleason, G. Ciullo, J. P. Ball, Y. Prok, D. S. Carman, Nikos Sparveris, S. Niccolai, A. Movsisyan, M. Ripani, E. Seder, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), CLAS, and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11)

Subjects
Single spin asymmetries, Hadron, fragmentation function, 01 natural sciences, Settore FIS/04 - Fisica Nucleare e Subnucleare, transverse momentum: momentum spectrum, Collins, hadron: production, Nuclear Experiment, Spin-½, Physics, deep inelastic scattering: semi-inclusive reaction, suppression, Collins fragmentation, hadron: energy, lcsh:QC1-999, Double spin asymmetries, Semi-inclusive deep-inelastic scattering, Transverse momentum distributions, High Energy Physics - Phenomenology, transverse, electron: scattering, cryogenics, spin: asymmetry, Jefferson Lab, Nuclear and High Energy Physics, pi: momentum, Quark, Socio-culturale, quark gluon: correlation, lepton: scattering, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], quark, pi: electroproduction, Nuclear physics, Pion, target: spin, deep inelastic scattering, CLAS, 0103 physical sciences, 010306 general physics, 010308 nuclear & particles physics, Scattering, High Energy Physics::Phenomenology, Deep inelastic scattering, Gluon, Automatic Keywords, [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph], High Energy Physics::Experiment, higher-dimensional, lcsh:Physics, experimental results, Lepton
Abstract

We present precision measurements of the target and beam-target spin asymmetries from neutral pion electroproduction in deep-inelastic scattering (DIS) using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. We scattered 6-GeV, longitudinally polarized electrons off longitudinally polarized protons in a cryogenic $^{14}$NH$_3$ target, and extracted double and single target spin asymmetries for $ep\rightarrow e^\prime\pi^0X$ in multidimensional bins in four-momentum transfer ($1.0, Comment: 18 preprint pages, 3 figures

Published
2018

14. Photon beam asymmetry Σ in the reaction γ→p→pω for E= 1.152 to 1.876 GeV

Author

G. Khachatryan, W. Kim, M. Battaglieri, N. K. Walford, G. Niculescu, L. Lanza, Michael Paolone, M. Bashkanov, S. Adhikari, H. Avakian, F. X. Girod, W. J. Briscoe, Laura Clark, B. McKinnon, P. Lenisa, T. Cao, M. Ungaro, I. J. D. MacGregor, F. Sabatié, I. I. Strakovsky, H. Voskanyan, A. Kim, E. De Sanctis, V. A. Nikonov, A. Deur, E. Pasyuk, J. W. Price, N. Dashyan, C. Gleason, G. Rosner, K. Hicks, V. Mokeev, P. Nadel-Turonski, V. Batourine, I. Bedlinskiy, D. I. Sober, S. Strauch, V. Crede, William Brooks, Dustin Keller, M. Defurne, Y. Ghandilyan, D. P. Watts, Barry Ritchie, Brian Raue, Alessandro Rizzo, C. Hanretty, H. Egiyan, E. Golovatch, R. Dupre, R. A. Montgomery, A. Celentano, R. W. Gothe, M. Khachatryan, Sylvester Joosten, B. S. Ishkhanov, G. Charles, Michael Wood, J. Ball, K. Hafidi, W. Phelps, H. S. Jo, A. V. Sarantsev, G. Ciullo, Y. Prok, D. I. Glazier, D. S. Carman, A. Simonyan, O. Cortes, N. A. Baltzell, C. Munoz Camacho, Nikos Sparveris, F. J. Klein, M. Ripani, M. Contalbrigo, Z. E. Meziani, E. L. Isupov, S. Niccolai, D. G. Jenkins, M. Osipenko, K. A. Griffioen, R. Paremuzyan, Eberhard Klempt, S. Boiarinov, N. Markov, V. P. Kubarovsky, A. Movsisyan, R. De Vita, Nicholas M. Harrison, O. Pogorelko, Gerard Gilfoyle, J. Zhang, S. M. Hughes, X. Wei, S. Pisano, D. Sokhan, I. Stankovic, A. V. Anisovich, C. A. Meyer, Z. Akbar, G. V. Fedotov, I. Niculescu, C. Salgado, P. L. Cole, A. I. Ostrovidov, K. Park, R. A. Schumacher, D. G. Ireland, H. Jiang, H. Hakobyan, S. Anefalos Pereira, Volker D. Burkert, A. S. Biselli, L. El Fassi, K. P. Adhikari, S. Stepanyan, E. Munevar, L. A. Net, Avraham Klein, Y. G. Sharabian, J. A. Fleming, Iu. Skorodumina, D. Heddle, G. Hollis, P. Eugenio, M. Taiuti, P. Collins, S. Procureur, K. L. Giovanetti, A. El Alaoui, Y. Ilieva, Nicholas Zachariou, A. Filippi, M. Khandaker, K. Livingston, M. Hattawy, D. Protopopescu, Z. W. Zhao, E. Voutier, Chaden Djalali, Michael Dugger, T. Mineeva, F. Cao, D. Adikaram, M. Guidal, G. D. Smith, M. Holtrop, Taya Chetry, and Sergey Kuleshov

Subjects
Physics, Nuclear and High Energy Physics, Photon, Meson, Proton, 010308 nuclear & particles physics, Partial wave analysis, Bremsstrahlung, Photon energy, 01 natural sciences, Nuclear physics, Pomeron, 0103 physical sciences, Nuclear Experiment, 010306 general physics, Nucleon
Abstract

Photon beam asymmetry Σ measurements for ω photoproduction in the reaction γ → p → ω p are reported for photon energies from 1.152 to 1.876 GeV. Data were taken using a linearly-polarized tagged photon beam, a cryogenic hydrogen target, and the CLAS spectrometer in Hall B at Jefferson Lab. The measurements obtained markedly increase the size of the database for this observable, extend coverage to higher energies, and resolve discrepancies in previously published data. Comparisons of these new results with predictions from a chiral-quark-based model and from a dynamical coupled-channels model indicate the importance of interferences between t-channel meson exchange and s- and u-channel contributions, underscoring sensitivity to the nucleon resonances included in those descriptions. Comparisons with the Bonn–Gatchina partial-wave analysis indicate the Σ data reported here help to fix the magnitudes of the interference terms between the leading amplitudes in that calculation (Pomeron exchange and the resonant portion of the J P = 3 / 2 + partial wave), as well as the resonant portions of the smaller partial waves with J P = 1 / 2 − , 3 / 2 − , and 5 / 2 + .

Published
2017

15. The Heavy Photon Search beamline and its performance

Author

F. X. Girod, M. Ungaro, C. Field, G. Kalicy, B. McKinnon, T. K. Nelson, T. Maruyama, A. P. Freyberger, S. Stepanyan, N. A. Baltzell, M. Holtrop, M. Ehrhart, K. Moffeit, S. Uemura, H. Vance, A. Odian, Hovanes Egiyan, R. Paremuzyan, J. Jaros, M. Oriunno, and M. Tiefenback

Subjects
Nuclear and High Energy Physics, Physics - Instrumentation and Detectors, Photon, Physics::Instrumentation and Detectors, FOS: Physical sciences, 01 natural sciences, Dark photon, High Energy Physics - Experiment, law.invention, Nuclear physics, High Energy Physics - Experiment (hep-ex), law, 0103 physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment, 010306 general physics, Instrumentation, Physics, Spectrometer, 010308 nuclear & particles physics, Detector, Collimator, Particle accelerator, Instrumentation and Detectors (physics.ins-det), Beamline, Cathode ray, Physics::Accelerator Physics
Abstract

The Heavy Photon Search (HPS) is an experiment to search for a hidden sector photon, aka a heavy photon or dark photon, in fixed target electroproduction at the Thomas Jefferson National Accelerator Facility (JLab). The HPS experiment searches for the e$^+$e$^-$ decay of the heavy photon with bump hunt and detached vertex strategies using a compact, large acceptance forward spectrometer, consisting of a silicon microstrip detector (SVT) for tracking and vertexing, and a PbWO$_4$ electromagnetic calorimeter for energy measurement and fast triggering. To achieve large acceptance and good vertexing resolution, the first layer of silicon detectors is placed just 10 cm downstream of the target with the sensor edges only 500 $\mu$m above and below the beam. Placing the SVT in such close proximity to the beam puts stringent requirements on the beam profile and beam position stability. As part of an approved engineering run, HPS took data in 2015 and 2016 at 1.05 GeV and 2.3 GeV beam energies, respectively. This paper describes the beam line and its performance during that data taking.

Published
2017

16. Exploring the Structure of the Bound Proton with Deeply Virtual Compton Scattering

Author

A. El Alaoui, Alessandro Rizzo, C. Ayerbe Gayoso, M. Khandaker, R. Paremuzyan, Nicholas Zachariou, O. Soto, Andrea Celentano, Nicholas M. Harrison, Gerard Gilfoyle, D. P. Watts, S. Fegan, D. Sokhan, V. Crede, K. Livingston, M. Garçon, Sandra K. Johnston, R. A. Montgomery, Jie Zhang, F. X. Girod, M. Battaglieri, M. Contalbrigo, G. Gavalian, E. Golovatch, S. Strauch, Aditya R. Khanal, S. Niccolai, A. Filippi, M. Ripani, R. Dupre, N A Baltzell, K. L. Giovanetti, A. D'Angelo, E. L. Isupov, G. Khachatryan, Dustin Keller, Larry Weinstein, P. Lenisa, Yordanka Ilieva, M. Defurne, N. Markov, Chaden Djalali, Michael Wood, Laura Clark, E. De Sanctis, F. Sabatié, D. Heddle, K. A. Griffioen, T. Mineeva, L. Barion, K. Hafidi, J. Poudel, Taya Chetry, C. Munoz Camacho, P. L. Cole, Iu. Skorodumina, G. Angelini, P. Rossi, T. B. Hayward, D. Protopopescu, Z. W. Zhao, B. McKinnon, F. Hauenstein, Friedrich Klein, L. Lanza, B. Torayev, A Fradi, S. Diehl, C. Salgado, V. P. Kubarovsky, D. Riser, G. Ciullo, O. Pogorelko, M. Mirazita, H. Egiyan, F. Bossu, G. Rosner, P. Eugenio, Y. Prok, D. S. Carman, L. El Fassi, E. Pasyuk, M. Taiuti, C. W. Kim, Zein-Eddine Meziani, F. Cao, M. L. Kabir, S. E. Kuhn, M. Hattawy, H. Voskanyan, A. I. Ostrovidov, D. G. Jenkins, I. J. D. MacGregor, M. Guidal, Rong Wang, N. Dashyan, D. G. Ireland, M Ehrhart, A. S. Biselli, N. Gevorgyan, R. W. Gothe, M. Holtrop, I. Bedlinskiy, Luciano Pappalardo, Martin K. Mayer, A. Deur, W. Kim, M. Khachatryan, Nikolaos Sparveris, W. K. Brooks, S. Adhikari, Y. G. Sharabian, R. De Vita, D. Marchand, H. S. Jo, X. Wei, R. A. Schumacher, S. Bültmann, T. A. Forest, S. Stepanyan, Simonetta Liuti, M. Ungaro, Y. Perrin, K. Hicks, P. Chatagnon, P. Nadel-Turonski, N. Tyler, J. A. Tan, E. Voutier, Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, CLAS, Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), and Université Grenoble Alpes (UGA)

Subjects
generalized parton distribution, Proton, EMC effect, Nuclear Theory, General Physics and Astronomy, Virtual particle, parton: distribution function, Parton, Electron, 01 natural sciences, 7. Clean energy, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), Electromagnetic probes, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Nuclear Experiment (nucl-ex), Form factors, Electromagnetic probes, Nuclear Structure, Deep Virtual Compton Scattering, Quark models, Electron-ion collisions, Nuclear structure & decays, Nucleon distribution, electron: beam, Nuclear Experiment, Physics, Settore FIS/04, Form factors, nucleon, matter: effect, kinematics, Quark models, Nucleon, spin: asymmetry, accelerator, FOS: Physical sciences, Socio-culturale, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Structure, Deep Virtual Compton Scattering, Nuclear physics, PE2_2, PE2_1, deeply virtual Compton scattering, CLAS, 0103 physical sciences, structure, 010306 general physics, PE2_3, Electron-ion collisions, Nuclear Physics, Scattering, Nuclear structure &amp, Compton scattering, Automatic Keywords, Physics::Accelerator Physics, High Energy Physics::Experiment, Nucleon distribution, spectrometer, decays, experimental results, photon: virtual
Abstract

In the past two decades, deeply virtual Compton scattering of electrons has been successfully used to advance our knowledge of the partonic structure of the free proton and investigate correlations between the transverse position and the longitudinal momentum of quarks inside the nucleon. Meanwhile, the structure of bound nucleons in nuclei has been studied in inclusive deep-inelastic lepton scattering experiments off nuclear targets, showing a significant difference in longitudinal momentum distribution of quarks inside the bound nucleon, known as the EMC effect. In this work, we report the first beam spin asymmetry (BSA) measurement of exclusive deeply virtual Compton scattering (DVCS) off a proton bound in $^4$He. The data used here were accumulated using a $6$ GeV longitudinally polarized electron beam incident on a pressurized $^4$He gaseous target placed within the CLAS spectrometer in Hall-B at the Thomas Jefferson National Accelerator Facility. The azimuthal angle ($\phi$) dependence of the BSA was studied in a wide range of virtual photon and scattered proton kinematics. The $Q^2$, $x_B$, and t dependencies of the BSA on the bound proton are compared with those on the free proton. In the whole kinematical region of our measurements, the BSA on the bound proton is smaller by 20\% to 40\%, indicating possible medium modification of its partonic structure.

Published
2019

17. The CLAS12 Data Acquisition System

Author

K. Livingston, B. Moffit, W. Moore, B. Raydo, I. Mandjavidze, D. Heddle, S. Boyarinov, W. Gu, N. A. Baltzell, C. Timmer, A. Celentano, R. De Vita, D. Abbott, V. Gyurjyan, G. Heyes, H. Dong, C. Cuevas, B. McKinnon, C. Dickover, E. Jastrzembski, C. Smith, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay

Subjects
Physics, Nuclear and High Energy Physics, data acquisition, 010308 nuclear & particles physics, business.industry, Detector, programming, 01 natural sciences, computer: network, Software, Data acquisition, CLAS, Control system, 0103 physical sciences, electronics: readout, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], control system, 010306 general physics, business, Instrumentation, performance, activity report, Computer hardware, electronics: design
Abstract

International audience; The CLAS12 Data Acquisition System was designed and built as part of the CLAS12 detector project in Hall B at Jefferson Laboratory. This article contains a full description of the system, including requirements, design, hardware, and software descriptions, as well as the achieved performance. The associated computing, network, and slow controls systems are also described.

Published
2020

18. The CLAS12 beamline and its performance

Author

Volker D. Burkert, J. Carvajal, R. De Vita, N. A. Baltzell, Y. G. Sharabian, B. A. Raue, Latifa Elouadrhiri, G. Kharashvili, N. Dashyan, S. Stepanyan, R. Paremuzyan, M. Ungaro, M. Tiefenback, A. Kim, and K. Wild

Subjects
Physics, Nuclear and High Energy Physics, Luminosity (scattering theory), 010308 nuclear & particles physics, business.industry, Detector, Collimator, Polarimeter, 01 natural sciences, law.invention, Optics, Beamline, law, 0103 physical sciences, Instrumentation (computer programming), Laser beam quality, 010306 general physics, business, Instrumentation, Beam (structure)
Abstract

This paper describes the Hall B beamline and its performance during the first year of data-taking operation using the CLAS12 detector. We review the beamline instrumentation used to measure and monitor the beam. This instrumentation led to excellent beam quality for energies ranging from 2.2 to 10.6 GeV at the design luminosity of 1 0 35 cm−2s−1. The instrumentation includes a Moller polarimeter, which can typically measure the beam polarization to an absolute precision of ∼ 2.5%.

Published
2020

19. Search for a dark photon in electroproduced e+e− pairs with the Heavy Photon Search experiment at JLab

Author

S. Paul, O. Moreno, M. Osipenko, M. Carpinelli, M. Garçon, B. Reese, H. Egiyan, Volker D. Burkert, P. H. Adrian, K. Livingston, L. Elouadrhiri, R. Essig, L. Colaneri, Bogdan Wojtsekhowski, A. Filippi, R. Dupre, M. Battaglieri, B. Raydo, N. Randazzo, William T. Cooper, M. Khandaker, S. Boyarinov, K. McCarty, A. Deur, M. Guidal, A. P. Freyberger, Norman A. Graf, C. Munoz Camacho, S. Uemura, M. Holtrop, S. Bueltmann, H. Szumila-Vance, K.C. Moffeit, Valeria Sipala, C. Field, M. T. Graham, R. Paremuzyan, M. Solt, F. X. Girod, A. D'Angelo, G. Charles, D. Calvo, R. De Vita, C. Cuevas, M. Bondì, Emanuele Leonora, G. Kalicy, D. Sokhan, Ryan Herbst, B. McKinnon, M. De Napoli, Philip Schuster, Alexander Grillo, M. Oriunno, Larry Weinstein, N. Dashyan, A. Celentano, Vitaliy Fadeyev, Y. G. Sharabian, B. Yale, S. Stepanyan, A. Simonyan, N. Gevorgyan, Natalia Toro, J. A. Jaros, N. A. Baltzell, V. P. Kubarovsky, G. Simi, Jeremy McCormick, S. Niccolai, H. Voskanyan, Alessandro Rizzo, A.C. Odian, T. Maruyama, M. Ungaro, T. K. Nelson, and K. A. Griffioen

Subjects
Coupling, Physics, Photon, Luminosity (scattering theory), 010308 nuclear & particles physics, 01 natural sciences, 7. Clean energy, Resonance (particle physics), Dark photon, Standard Model, Nuclear physics, 0103 physical sciences, Cathode ray, Invariant mass, 010306 general physics
Abstract

The Heavy Photon Search experiment took its first data in a 2015 engineering run using a 1.056 GeV, 50 nA electron beam provided by CEBAF at the Thomas Jefferson National Accelerator Facility, searching for a prompt, electroproduced dark photon with a mass between 19 and 81 MeV/c2. A search for a resonance in the e+e- invariant mass distribution, using 1.7 days (1170 nb-1) of data, showed no evidence of dark photon decays above the large QED background, confirming earlier searches and demonstrating the full functionality of the experiment. Upper limits on the square of the coupling of the dark photon to the standard model photon are set at the level of 6×10-6. Future runs with higher luminosity will explore new territory.

Published
2018

20. Measurement of Unpolarized and Polarized Cross Sections for Deeply Virtual Compton Scattering on the Proton at Jefferson Laboratory with CLAS

Author

F. Cao, W. Phelps, M. Guidal, E. Pasyuk, N. Dashyan, P. Lenisa, Andrea Celentano, M. Holtrop, S. Procureur, W. Gohn, S. E. Kuhn, G. Charles, M. J. Amaryan, H. S. Jo, H. Y. Lu, H. Voskanyan, B. McKinnon, Iu. Skorodumina, Friedrich Klein, Z. W. Zhao, A. I. Ostrovidov, R. A. Montgomery, Y. Prok, F. Sabatié, David M. Keller, Maxime Defurne, B. Guegan, K. A. Griffioen, H. Hakobyan, P. Stoler, A. Kim, M. Mirazita, A. El Alaoui, A. Filippi, N. Markov, A. Fradi, Latifa Elouadrhiri, X. Wei, G. Rosner, Taya Chetry, C. A. Meyer, I. Balossino, N. Gevorgyan, S. Johnston, K. L. Giovanetti, E. L. Isupov, G. V. Fedotov, K. Hicks, Y. Ghandilyan, Nicholas Zachariou, P. Eugenio, G. Niculescu, V. Batourine, D. G. Ireland, Sergey Kuleshov, M. Ripani, A. Deur, L. Guo, T. Mineeva, K. P. Adhikari, J. A. Tan, M. L. Kabir, S. Niccolai, Volker D. Burkert, W. K. Brooks, D. P. Watts, B. S. Ishkhanov, S. Adhikari, A. S. Biselli, D. Heddle, M. Battaglieri, C. Gleason, M. Khachatryan, D. G. Jenkins, M. Ungaro, R. De Vita, G. Khachatryan, E. Golovatch, R. Dupre, K. Park, Y. Ilieva, Nikolaos Sparveris, L. Lanza, R. W. Gothe, W. Kim, I. Bedlinskiy, K. Livingston, C. Munoz Camacho, M. Hattawy, R. A. Schumacher, M. Osipenko, P. Rossi, W. J. Briscoe, A. D'Angelo, R. G. Fersch, V. P. Kubarovsky, P. Nadel-Turonski, D. Riser, M. Khandaker, S. Stepanyan, R. Paremuzyan, K. Hafidi, S. Bültmann, T. A. Forest, P. L. Cole, Sylvester Joosten, O. Pogorelko, S. Diehl, S. Anefalos Pereira, Avraham Klein, Nicholas M. Harrison, Gerard Gilfoyle, J. W. Price, I. J. D. MacGregor, M. Contalbrigo, Martin Wood, C. Hanretty, L. Barion, C. Salgado, M. Taiuti, J. Zhang, D. Protopopescu, Victor Mokeev, Z. Akbar, M. Garçon, E. Voutier, Y. G. Sharabian, G. Ciullo, J. P. Ball, D. S. Carman, A. Rizzo, A. Movsisyan, L. El Fassi, Zein-Eddine Meziani, M. E. McCracken, F. X. Girod, O. Cortes, S. Boiarinov, Chaden Djalali, G. D. Smith, S. Strauch, G. Gavalian, B. A. Clary, N. Hirlinger Saylor, Michael Paolone, N. A. Baltzell, K. Joo, H. Egiyan, Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, CLAS, and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11)

Subjects
electron p: deep inelastic scattering, interference: Bethe-Heitler, Nuclear and High Energy Physics, generalized parton distribution, Proton, accelerator, electron: polarized beam, Hadronic Physics and QCD, FOS: Physical sciences, Socio-culturale, parton: distribution function, Parton, Newport News CEBAF Linac, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], momentum transfer dependence, 01 natural sciences, beam: energy, High Energy Physics - Experiment, Settore FIS/04 - Fisica Nucleare e Subnucleare, x-dependence, Nuclear physics, Cross section (physics), High Energy Physics - Experiment (hep-ex), spectrometer: acceptance, High Energy Physics - Phenomenology (hep-ph), deeply virtual Compton scattering, CLAS, 0103 physical sciences, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Experiment, Quantum chromodynamics, Physics, Spectrometer, 010308 nuclear & particles physics, Compton scattering, cross section: difference, HERA, magnetic spectrometer, photon: electroproduction, High Energy Physics - Phenomenology, kinematics, [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph], Nucleon, channel cross section: measured, experimental results
Abstract

This paper reports the measurement of polarized and unpolarized cross sections for the ep -> e'p' reaction, which is comprised of Deeply Virtual Compton Scattering (DVCS) and Bethe-Heitler (BH) processes, at an electron beam energy of 5.88 GeV at the Thomas Jefferson National Accelerator Facility using the Large Acceptance Spectrometer CLAS. The unpolarized cross sections and polarized cross section differences have been measured over broad kinematics, 0.10 < x_B < 0.58, 1.0 < Q^2 < 4.8 GeV^2, and 0.09 < -t < 2.00 GeV^2. The results are found to be consistent with previous CLAS data, and these new data are discussed in the framework of the generalized parton distribution approach. Calculations with two widely used phenomenological models, denoted VGG and KMSC, are approximately compatible with the experimental results over a large portion of the kinematic range of the data., 27 pages, 24 figures, Accepted for publication in PRC

Published
2018

21. Determination of the proton spin structure functions for 0.05<Q2<5GeV2 using CLAS

Author

N. Harrison, V. Crede, Y. Prok, A. Simonyan, R. A. Montgomery, P. Lenisa, N. Zachariou, H. Egiyan, L. Clark, N. K. Walford, M. Ungaro, N. Dashyan, R. W. Gothe, A. D'Angelo, G. P. Gilfoyle, C. Salgado, L. Colaneri, P. Bosted, P. Eugenio, I. Balossino, R. G. Fersch, Friedrich Klein, E. L. Isupov, M. Taiuti, W. Phelps, M. Contalbrigo, G. Gavalian, F. Cao, K. Hicks, G. Murdoch, P. Roy, M. Guidal, Taya Chetry, G. E. Dodge, C. Hanretty, M. Khandaker, M. Holtrop, M. Garçon, K. Hafidi, I. Bedlinskiy, J. A. Fleming, J. Ball, M. Hattawy, M. Osipenko, Iu. Skorodumina, B. S. Ishkhanov, D. Protopopescu, D. Heddle, D. Keller, Z. Akbar, Marco Ripani, J. Zhang, Michael Paolone, C. Djalali, C. A. Meyer, E. Voutier, G. V. Fedotov, O. Cortes, D. P. Watts, K. Griffioen, H. Voskanyan, V. Kubarovsky, C. Keith, W. K. Brooks, P. Rossi, Ye Tian, F. Sabatié, L. B. Weinstein, S. L. Careccia, I. I. Strakovsky, A. Rizzo, A. Deur, C. Gleason, R. Paremuzyan, W. Kim, D. Sokhan, S. Pisano, L. Elouadrhiri, G. Niculescu, S. E. Kuhn, D. Riser, A. El Alaoui, S. Stepanyan, O. Pogorelko, H. Avakian, B. A. Raue, A. I. Ostrovidov, G. Asryan, D. G. Ireland, Y. Ilieva, Volker D. Burkert, A. S. Biselli, R. Dupre, K. L. Giovanetti, G. Ciullo, D. A. Jenkins, K. Livingston, D. S. Carman, Nikos Sparveris, S. Niccolai, X. Wei, L. Lanza, V. G. Lagerquist, B. Torayev, E. Pasyuk, I. Stankovic, A. Movsisyan, N. Guler, M. Mirazita, C. Munoz Camacho, N. Compton, Hrachya Hakobyan, B. McKinnon, E. De Sanctis, A. Klein, H. Y. Lu, R. De Vita, S. Anefalos Pereira, K. Joo, S. Chandavar, A. Filippi, M. J. Amaryan, E. Fanchini, L. Guo, J. W. Price, S. M. Hughes, R. Minehart, R. A. Schumacher, V. Mokeev, K. P. Adhikari, T. A. Forest, J. Pierce, S. Bultmann, E. Golovatch, P. Nadel-Turonski, I. Niculescu, S. Adhikari, G. Khachatryan, W. J. Briscoe, G. Charles, L. El Fassi, P. L. Cole, Andrea Celentano, A. Kim, G. D. Smith, F. X. Girod, S. Strauch, M. Khachatryan, Y. G. Sharabian, G. Rosner, N. A. Baltzell, Y. Ghandilyan, K. Park, and M. Battaglieri

Subjects
Quantum chromodynamics, Physics, Particle physics, Proton, 010308 nuclear & particles physics, Virtual particle, Parton, Deep inelastic scattering, 01 natural sciences, Nuclear physics, 0103 physical sciences, Proton spin crisis, High Energy Physics::Experiment, Operator product expansion, Nuclear Experiment, 010306 general physics, Spin-½
Abstract

We present the results of our final analysis of the full data set of g1p(Q2), the spin structure function of the proton, collected using CLAS at Jefferson Laboratory in 2000–2001. Polarized electrons with energies of 1.6, 2.5, 4.2, and 5.7 GeV were scattered from proton targets (NH315 dynamically polarized along the beam direction) and detected with CLAS. From the measured double spin asymmetries, we extracted virtual photon asymmetries A1p and A2p and spin structure functions g1p and g2p over a wide kinematic range (0.05 GeV2

Published
2017

22. Measurement of the differential and total cross sections of the γd→K0Λ(p) reaction within the resonance region

Author

H. Hakobyan, M. Taiuti, Dustin Keller, N. Compton, N. Dashyan, D. I. Glazier, R. De Vita, Michael Wood, K. Hafidi, Laura Clark, Yordanka Ilieva, X. Wei, C. E. Hyde, A. Simonyan, M. Osipenko, L. Guo, Alessandro Rizzo, S. Anefalos Pereira, K. Hicks, R. Paremuzyan, R. A. Schumacher, W. Phelps, V. P. Kubarovsky, V. Crede, A. El Alaoui, J. A. Fleming, O. Pogorelko, S. M. Hughes, P. Nadel-Turonski, G. Murdoch, R. A. Montgomery, Michael Paolone, G. Gavalian, N. K. Walford, M. Camp, G. Charles, V. Mokeev, C. Gleason, Nicholas Zachariou, E. De Sanctis, K. P. Adhikari, Nicholas M. Harrison, T. Cao, H. Avakian, H. S. Jo, F. X. Girod, N. Markov, I. J. D. MacGregor, D. Heddle, C. Hanretty, Barry Ritchie, H. Voskanyan, S. Pisano, P. Lenisa, M. Contalbrigo, Avraham Klein, D. Sokhan, F. Sabatié, H. Y. Lu, G. Rosner, M. Khachatryan, I. Stankovic, Philip L. Cole, Z. Akbar, S. Adhikari, B. McKinnon, Nikolaos Sparveris, I. Bedlinskiy, E. Munevar, W. Kim, P. L. Cole, K. Livingston, Y. Ghandilyan, I. Niculescu, Friedrich Klein, D. G. Jenkins, G. Niculescu, B. S. Ishkhanov, A. D'Angelo, Taya Chetry, R. W. Gothe, Eberhard Klempt, M. Mirazita, L. El Fassi, V. Batourine, J. Zhang, S. Stepanyan, G. Khachatryan, Brian Raue, J. W. Price, Latifa Elouadrhiri, C. A. Meyer, Sergey Kuleshov, M. Ripani, M. Ungaro, A. I. Ostrovidov, K. Park, G. V. Fedotov, F. Cao, D. G. Ireland, V. A. Nikonov, Volker D. Burkert, A. S. Biselli, W. J. Briscoe, K. Joo, C. Munoz Camacho, I. I. Strakovsky, M. Guidal, Y. G. Sharabian, G. Ciullo, Y. Prok, T. Mineeva, D. S. Carman, D. Protopopescu, A. Deur, E. Voutier, S. Niccolai, A. Movsisyan, Iu. Skorodumina, W. K. Brooks, G. D. Smith, M. Holtrop, C. E. Taylor, E. Golovatch, R. Dupre, S. Strauch, D. P. Watts, H. Egiyan, A. V. Sarantsev, M. Battaglieri, B. Torayev, K. L. Giovanetti, A. Filippi, M. Khandaker, O. Cortes, E. L. Isupov, A. Fradi, Sylvester Joosten, L. Lanza, Eugene Pasyuk, Andrea Celentano, C. Djalali, N. A. Baltzell, C. Salgado, K. A. Griffioen, A. Trivedi, and P. Eugenio

Subjects
Physics, Particle physics, 010308 nuclear & particles physics, Partial wave analysis, Quark model, Gamma ray, Bremsstrahlung, Resonance, Lambda, 01 natural sciences, Particle identification, Nuclear physics, 0103 physical sciences, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, Nucleon
Abstract

We report the first measurement of differential and total cross sections for the $\ensuremath{\gamma}d\ensuremath{\rightarrow}{K}^{0}\mathrm{\ensuremath{\Lambda}}(p)$ reaction, using data from the CLAS detector at the Thomas Jefferson National Accelerator Facility. Data collected during two separate experimental runs were studied with photon-energy coverage 0.8--3.6 GeV and 0.5-- 2.6 GeV, respectively. The two measurements are consistent giving confidence in the method and determination of systematic uncertainties. The cross sections are compared with predictions from the KAON-MAID theoretical model (without kaon exchange), which deviate from the data at higher $W$ and at forward kaon angles. These data, along with previously published cross sections for ${K}^{+}\mathrm{\ensuremath{\Lambda}}$ photoproduction, provide essential constraints on the nucleon resonance spectrum. A first partial wave analysis was performed that describes the data without the introduction of new resonances.

Published
2017

23. First Exclusive Measurement of Deeply Virtual Compton Scattering off He4 : Toward the 3D Tomography of Nuclei

Author

M. J. Amaryan, Laura Clark, C. Gleason, P. Lenisa, W. Phelps, H. Moutarde, X. Wei, K. A. Griffioen, B. S. Ishkhanov, K. L. Giovanetti, Taya Chetry, M. Hattawy, Hovanes Egiyan, Larry Weinstein, G. Ciullo, J. P. Ball, Y. Prok, D. S. Carman, P. Eugenio, E. Golovatch, S. Strauch, J. W. Price, Friedrich Klein, L. Guo, Alessandro Rizzo, C. Munoz Camacho, D. G. Ireland, E. Voutier, Latifa Elouadrhiri, R. De Vita, V. Crede, M. Taiuti, C. Djalali, Michael Paolone, A. Movsisyan, O. Cortes, E. L. Isupov, S. Niccolai, Z. W. Zhao, C. A. Meyer, H. Y. Lu, L. Lanza, Whitney Armstrong, A. I. Ostrovidov, K. Park, G. V. Fedotov, D. P. Watts, G. Rosner, R. A. Montgomery, A. Celentano, Martin K. Mayer, R. W. Gothe, K. Livingston, A. Deur, H. Jiang, Volker D. Burkert, A. S. Biselli, D. G. Jenkins, R. Paremuzyan, Sergey Kuleshov, M. Khachatryan, A. Simonyan, Y. Ghandilyan, V. I. Mokeev, D. Heddle, H. Hakobyan, M. H. Wood, R. Dupre, S. Boiarinov, L. Colaneri, Iu. Skorodumina, S. Adhikari, S. Anefalos Pereira, S. Fegan, Jie Zhang, I. Niculescu, F. Cao, E. Pasyuk, Nikolaos Sparveris, N. Markov, K. Hicks, D. Adikaram, B. Torayev, M. Guidal, G. Charles, F. X. Girod, Z. E. Meziani, Nicholas M. Harrison, Gerard Gilfoyle, I. Bedlinskiy, N. A. Baltzell, C. Hanretty, W. Kim, P. Nadel-Turonski, William Brooks, A. Filippi, G. D. Smith, M. Holtrop, Lorenzo Zana, G. Khachatryan, M. Battaglieri, G. Niculescu, E. Seder, R. G. Fersch, F. Sabatié, W. Gohn, P. Rossi, V. P. Kubarovsky, D. Sokhan, P. L. Cole, M. Khandaker, O. Pogorelko, D. Protopopescu, B. G. Ritchie, M. Bashkanov, R. A. Schumacher, M. Ungaro, S. M. Hughes, M. Garçon, N. Dashyan, A. D'Angelo, E. De Sanctis, Sylvester Joosten, B. McKinnon, M. E. McCracken, L. A. Net, L. El Fassi, C. Salgado, M. Osipenko, Dustin Keller, A. El Alaoui, N. K. Walford, Y. Perrin, T. Mineeva, Nicholas Zachariou, S. Bültmann, M. Mirazita, E. Phelps, K. P. Adhikari, T. A. Forest, K. Hafidi, N. Gevorgyan, I. J. D. MacGregor, V. Batourine, H. Avakian, S. Stepanyan, Y. G. Sharabian, S. Pisano, K. Joo, Simonetta Liuti, Avraham Klein, M. Contalbrigo, H. Voskanyan, A. Kim, W. J. Briscoe, A. Fradi, S. E. Kuhn, J. A. Fleming, Z. Akbar, and M. Ripani

Subjects
Physics, Particle physics, Time projection chamber, Photon, Proton, Meson, 010308 nuclear & particles physics, Compton scattering, General Physics and Astronomy, Electron, HERA, 01 natural sciences, 7. Clean energy, Nuclear physics, Recoil, 0103 physical sciences, Physics::Accelerator Physics, Nuclear Experiment, 010306 general physics
Abstract

We report on the first measurement of the beam-spin asymmetry in the exclusive process of coherent deeply virtual Compton scattering off a nucleus. The experiment uses the 6 GeV electron beam from the Continuous Electron Beam Accelerator Facility (CEBAF) accelerator at Jefferson Lab incident on a pressurized $^{4}\mathrm{He}$ gaseous target placed in front of the CEBAF Large Acceptance Spectrometer (CLAS). The scattered electron is detected by CLAS and the photon by a dedicated electromagnetic calorimeter at forward angles. To ensure the exclusivity of the process, a specially designed radial time projection chamber is used to detect the recoiling $^{4}\mathrm{He}$ nuclei. We measure beam-spin asymmetries larger than those observed on the free proton in the same kinematic domain. From these, we are able to extract, in a model-independent way, the real and imaginary parts of the only $^{4}\mathrm{He}$ Compton form factor, ${\mathcal{H}}_{A}$. This first measurement of coherent deeply virtual Compton scattering on the $^{4}\mathrm{He}$ nucleus, with a fully exclusive final state via nuclear recoil tagging, leads the way toward 3D imaging of the partonic structure of nuclei.

Published
2017

24. Differential cross section measurements for γn→π−p above the first nucleon resonance region

Author

P. Eugenio, W. Kim, G. Niculescu, B. S. Ishkhanov, A. E. Kudryavtsev, A. Simonyan, Z. E. Meziani, V. P. Kubarovsky, S. M. Hughes, D. Adikaram, M. Guidal, X. Wei, K. Livingston, D. P. Watts, Michael Paolone, I. Bedlinskiy, H. Voskanyan, H. S. Jo, C. Salgado, A. Celentano, R. W. Gothe, R. A. Schumacher, Maxime Defurne, Dustin Keller, P. Lenisa, Jie Zhang, Michael Wood, K. Hafidi, P. Mattione, R. Fersch, G. D. Smith, M. Holtrop, G. Ciullo, J. P. Ball, Y. Prok, D. S. Carman, R. Paremuzyan, M. Osipenko, Alfred Švarc, Nicholas M. Harrison, Gerard Gilfoyle, Nikos Sparveris, I. I. Strakovsky, R. De Vita, S. V. Kuleshov, E. Voutier, K. P. Adhikari, D. Sokhan, S. Stepanyan, K. L. Giovanetti, N. Markov, A. Deur, D. G. Jenkins, A. Movsisyan, A. El Alaoui, Y. Ilieva, Nicholas Zachariou, Friedrich Klein, G. Rosner, N. K. Walford, T. Cao, S. Pisano, F. X. Girod, I. J. D. MacGregor, Laura Clark, Avraham Klein, P. L. Cole, Brian Raue, M. Bashkanov, S. Adhikari, B. McKinnon, S. Anefalos Pereira, S. Niccolai, M. Contalbrigo, O. Pogorelko, Z. W. Zhao, Victor Mokeev, A. I. Ostrovidov, A. Filippi, M. Ungaro, K. Park, I. Niculescu, J. W. Price, M. Taiuti, M. Ripani, D. Protopopescu, D. G. Ireland, V. Batourine, M. Khandaker, Z. Akbar, H. Jiang, E. De Sanctis, A. D'Angelo, Y. Ghandilyan, Volker D. Burkert, A. S. Biselli, O. Cortes, V. Crede, H. Hakobyan, K. Joo, L. El Fassi, Hovanes Egiyan, C. Munoz Camacho, E. L. Isupov, D. Heddle, E. Golovatch, G. Khachatryan, K. Hicks, R. A. Montgomery, P. Nadel-Turonski, Chaden Djalali, S. Boiarinov, Michael Dugger, T. Mineeva, G. Hollis, Taya Chetry, W. Phelps, W. J. Briscoe, Alessandro Rizzo, C. Hanretty, S. Procureur, A. Fradi, Ron L. Workman, S. Strauch, L. Lanza, Eugene Pasyuk, L. A. Net, N. A. Baltzell, R. Dupre, M. Battaglieri, K. A. Griffioen, Y. G. Sharabian, M. Khachatryan, G. Charles, J. A. Fleming, F. Sabatié, C. A. Meyer, G. V. Fedotov, Iu. Skorodumina, G. Murdoch, C. Gleason, Barry Ritchie, M. Hattawy, Sylvester Joosten, A. Kim, N. Dashyan, I. Stankovic, and V. E. Tarasov

Subjects
Physics, Particle physics, Photon, 010308 nuclear & particles physics, Bremsstrahlung, Resonance, State (functional analysis), 01 natural sciences, Particle identification, Pion, Amplitude, 0103 physical sciences, Atomic physics, 010306 general physics, Nucleon
Abstract

The quasifree $\ensuremath{\gamma}d\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}p(p)$ differential cross section has been measured with CLAS at photon beam energies ${E}_{\ensuremath{\gamma}}$ from 0.445 to 2.510 GeV (corresponding to $W$ from 1.311 to 2.366 GeV) for pion center-of-mass angles $cos{\ensuremath{\theta}}_{\ensuremath{\pi}}^{c.m.}$ from $\ensuremath{-}0.72$ to 0.92. A correction for final state interactions has been applied to these data to extract the $\ensuremath{\gamma}n\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}p$ differential cross sections. These cross sections are quoted in 8428 $({E}_{\ensuremath{\gamma}},cos{\ensuremath{\theta}}_{\ensuremath{\pi}}^{c.m.})$ bins, a factor of nearly 3 increase in the world statistics for this channel in this kinematic range. These new data help to constrain coupled-channel analysis fits used to disentangle the spectrum of ${N}^{*}$ resonances and extract their properties. Selected photon decay amplitudes ${N}^{*}\ensuremath{\rightarrow}\ensuremath{\gamma}n$ at the resonance poles are determined for the first time and are reported here.

Published
2017

25. Measurements of ep→e′π+π−p′ cross sections with CLAS at 1.40GeV<W<2.0 GeV and 2.0GeV2<Q2<5.0GeV2

Author

Y. Ilieva, W. Kim, Nicholas Zachariou, G. Niculescu, L. Colaneri, C. Salgado, J. W. Price, Latifa Elouadrhiri, H. Y. Lu, I. Stankovic, H. Hakobyan, D. Protopopescu, M. Garçon, E. Voutier, G. V. Fedotov, B. G. Ritchie, R. G. Fersch, Taya Chetry, K. Park, V. I. Mokeev, C. Munoz Camacho, G. Murdoch, M. Osipenko, D. Heddle, C. Gleason, D. G. Ireland, P. L. Cole, H. Jiang, P. Eugenio, O. Cortes, E. L. Isupov, Laura Clark, M. Hattawy, P. Lenisa, Volker D. Burkert, Ye Tian, A. S. Biselli, W. Phelps, I. Niculescu, D. I. Glazier, Sergey Kuleshov, K. Livingston, S. Adhikari, R. De Vita, B. McKinnon, B. Torayev, X. Wei, Jie Zhang, D. Adikaram, M. Guidal, G. Gavalian, M. J. Amaryan, Eugene Pasyuk, S. Anefalos Pereira, G. D. Smith, M. Holtrop, M. Mirazita, I. I. Strakovsky, V. Batourine, V. Crede, A. Deur, Y. G. Sharabian, Michael Paolone, R. A. Schumacher, E. De Sanctis, S. Niccolai, R. Paremuzyan, R. A. Montgomery, K. L. Giovanetti, A. Kim, Nicholas M. Harrison, Gerard Gilfoyle, W. K. Brooks, J. A. Fleming, D. Sokhan, N. Markov, S. Bültmann, A. D'Angelo, D. G. Jenkins, K. P. Adhikari, T. A. Forest, E. Munevar, Avraham Klein, F. X. Girod, A. Filippi, L. El Fassi, M. Ungaro, K. Hicks, A. Trivedi, M. Khandaker, M. Ripani, I. Bedlinskiy, Friedrich Klein, T. Mineeva, Brian Raue, Iu. Skorodumina, L. Guo, E. Golovatch, R. Dupre, Alessandro Rizzo, K. Joo, C. Hanretty, G. Charles, C. Djalali, F. Sabatié, G. Khachatryan, K. A. Griffioen, P. Nadel-Turonski, B. S. Ishkhanov, W. J. Briscoe, Sylvester Joosten, L. Lanza, S. Procureur, M. C. Kunkel, S. Strauch, M. Battaglieri, Y. Ghandilyan, M. Contalbrigo, M. Taiuti, Z. Akbar, N. K. Walford, T. Cao, I. J. D. MacGregor, A. Celentano, R. W. Gothe, G. Ciullo, J. P. Ball, Y. Prok, D. S. Carman, N. A. Baltzell, Nikos Sparveris, Dustin Keller, A. Movsisyan, N. Dashyan, Michael Wood, K. Hafidi, A. Simonyan, V. P. Kubarovsky, D. Riser, O. Pogorelko, S. M. Hughes, H. Avakian, H. Voskanyan, and A. El Alaoui

Subjects
Nuclear physics, Baryon, Scattering cross-section, Physics, Particle physics, 010308 nuclear & particles physics, 0103 physical sciences, Pi interaction, 010306 general physics, Nucleon, 01 natural sciences, Resonance (particle physics), Energy (signal processing)
Abstract

This paper reports new exclusive cross sections for $ep\ensuremath{\rightarrow}{e}^{\ensuremath{'}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{p}^{\ensuremath{'}}$ using the CLAS detector at Jefferson Laboratory. These results are presented for the first time at photon virtualities $2.0\phantom{\rule{0.16em}{0ex}}{\mathrm{GeV}}^{2}\phantom{\rule{4pt}{0ex}}l{Q}^{2}l5.0\phantom{\rule{4pt}{0ex}}{\mathrm{GeV}}^{2}$ in the center-of-mass energy range 1.4 GeV $lWl$ 2.0 GeV, which covers a large part of the nucleon resonance region. Using a model developed for the phenomenological analysis of electroproduction data, we see strong indications that the relative contributions from the resonant cross sections at $Wl1.74$ GeV increase with ${Q}^{2}$. These data considerably extend the kinematic reach of previous measurements. Exclusive $ep\ensuremath{\rightarrow}{e}^{\ensuremath{'}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{p}^{\ensuremath{'}}$ cross section measurements are of particular importance for the extraction of resonance electrocouplings in the mass range above 1.6 GeV.

Published
2017

26. A Radial Time Projection Chamber for $\alpha$ detection in CLAS at JLab

Author

S. Minutoli, A. El Alaoui, Paolo Musico, S. E. Kuhn, M. Battaglieri, B. Torayev, R. De Vita, R. Dupre, K. Hafidi, S. Stepanyan, S. Bueltmann, N. A. Baltzell, Y. Perrin, E. Voutier, A. Celentano, Katya Kosheleva, M. Hattawy, M. Oliver, L. El Fassi, H. C. Fenker, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Institut de Physique Nucléaire d'Orsay ( IPNO ), Université Paris-Sud - Paris 11 ( UP11 ) -Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire de Physique Subatomique et de Cosmologie ( LPSC ), and Université Joseph Fourier - Grenoble 1 ( UJF ) -Institut polytechnique de Grenoble - Grenoble Institute of Technology ( Grenoble INP ) -Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique ( CNRS ) -Université Grenoble Alpes ( UGA )

Subjects
Nuclear reaction, Nuclear and High Energy Physics, Meson production, Physics - Instrumentation and Detectors, Nuclear Theory, Measure (physics), Nuclear physics, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, time projection chamber: design, 010305 fluids & plasmas, Gas electron multipliers, High Energy Physics - Experiment, helium: nucleus, [ PHYS.HEXP ] Physics [physics]/High Energy Physics - Experiment [hep-ex], CLAS, 0103 physical sciences, Calibration, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], meson: production, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], [ PHYS.NEXP ] Physics [physics]/Nuclear Experiment [nucl-ex], 010306 general physics, Nuclear Experiment, [ PHYS.PHYS.PHYS-INS-DET ] Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Instrumentation, Alpha particles, nucleus: recoil, Physics, deeply virtual Compton scattering: coherence, Time projection chamber, Spectrometer, Compton scattering, Alpha particle, calibration, sensitivity, DVCS, performance
Abstract

A new Radial Time Projection Chamber (RTPC) was developed at the Jefferson Laboratory to track low-energy nuclear recoils for the purpose of measuring exclusive nuclear reactions, such as coherent Deeply Virtual Compton Scattering and coherent meson production off $^4$He. In such processes, the $^4$He nucleus remains intact in the final state, however the CEBAF Large Acceptance Spectrometer (CLAS) cannot track the low energy $\alpha$ particles. In 2009, we carried out measurements using the CLAS spectrometer supplemented by the RTPC positioned directly around a gaseous $^4$He target, allowing a detection threshold as low as 12$\sim$MeV for $^4$He. This article discusses the design, principle of operation, calibration methods and the performances of this RTPC.

Published
2017

27. Measurement of two-photon exchange effect by comparing elastic e±p cross sections

Author

V. Crede, D. A. Jenkins, Lorenzo Zana, Y. G. Sharabian, L. Lanza, Hovanes Egiyan, C. Munoz Camacho, K. Livingston, L. Clark, G. V. Fedotov, P. Lenisa, C. Salgado, L. El Fassi, H. Voskanyan, K. A. Griffioen, Jie Zhang, B. McKinnon, M. D. Mestayer, O. Cortes, E. L. Isupov, Andrei Afanasev, S. Boiarinov, M. Taiuti, K. P. Adhikari, L. Guo, M. Mirazita, Z. Akbar, R. Fersch, Alessandro Rizzo, S. E. Kuhn, A. I. Ostrovidov, S. Stepanyan, N. Gevorgyan, V. Batourine, F. X. Girod, C. Hanretty, G. Khachatryan, J. A. Fleming, K. Park, N. Compton, C. Gleason, P. Eugenio, D. G. Ireland, K. L. Giovanetti, H. Jiang, W. Gohn, Larry Weinstein, V. P. Kubarovsky, W. J. Briscoe, Volker D. Burkert, R. Paremuzyan, J. W. Price, V. I. Mokeev, A. Ni, O. Pogorelko, S. M. Hughes, J. Ball, W. Kim, A. S. Biselli, M. Hattawy, Friedrich Klein, E. Golovatch, G. Niculescu, Gerard Gilfoyle, Taya Chetry, D. Heddle, D. Protopopescu, R. Dupre, E. Voutier, Michael Paolone, S. Strauch, D. Sokhan, Dustin Keller, I. Bedlinskiy, Brian Raue, P. Rossi, R. De Vita, Z. W. Zhao, A. D'Angelo, I. Zonta, F. Sabatié, Michael Wood, K. Hafidi, K. Hicks, Eugene Pasyuk, X. Wei, B. Torayev, P. L. Cole, N. K. Walford, S. Anefalos Pereira, E. Seder, W. Phelps, Andrew Puckett, D. Rimal, A. Filippi, Sergey Kuleshov, A. Deur, A. El Alaoui, M. Osipenko, M. Contalbrigo, Y. Ilieva, M. Khandaker, Nikolaos Sparveris, N. A. Baltzell, A. Fradi, Nicholas Zachariou, I. J. D. MacGregor, R. A. Badui, G. Rosner, V. Sytnik, L. Colaneri, Y. Ghandilyan, N. Markov, S. Pisano, N. Dashyan, P. Roy, Chaden Djalali, D. Adikaram, Iu. Skorodumina, I. Stankovic, R. W. Gothe, G. D. Smith, M. Holtrop, B. S. Ishkhanov, G. Ciullo, Y. Prok, D. S. Carman, N. Harrison, S. Niccolai, A. Movsisyan, P. Nadel-Turonski, Sylvester Joosten, M. Battaglieri, M. Ungaro, R. A. Schumacher, S. Bültmann, T. A. Forest, E. Munevar, Avraham Klein, William Brooks, Andrea Celentano, H. Y. Lu, I. Niculescu, J. Arrington, E. Fanchini, D. P. Watts, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), and CLAS Collaboration

Subjects
ratio, Proton, radiative-corrections, Socio-culturale, FOS: Physical sciences, Electron, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Settore FIS/04 - Fisica Nucleare e Subnucleare, Electron-proton scattering, Nuclear physics, 0103 physical sciences, form-factors, positron-proton, 4-momentum transfers, clas, hydrogen, beam, Nuclear Experiment (nucl-ex), Nuclear Experiment, 010306 general physics, Elastic scattering, Physics, 010308 nuclear & particles physics, Scattering, Electric form factor, Physics::Accelerator Physics, High Energy Physics::Experiment, Atomic physics, Electron scattering, Beam (structure), Lepton
Abstract

[Background] The electromagnetic form factors of the proton measured by unpolarized and polarized electron scattering experiments show a significant disagreement that grows with the squared four momentum transfer ($Q^{2}$). Calculations have shown that the two measurements can be largely reconciled by accounting for the contributions of two-photon exchange (TPE). TPE effects are not typically included in the standard set of radiative corrections since theoretical calculations of the TPE effects are highly model dependent, and, until recently, no direct evidence of significant TPE effects has been observed. [Purpose] We measured the ratio of positron-proton to electron-proton elastic-scattering cross sections in order to determine the TPE contribution to elastic electron-proton scattering and thereby resolve the proton electric form factor discrepancy. [Methods] We produced a mixed simultaneous electron-positron beam in Jefferson Lab's Hall B by passing the 5.6 GeV primary electron beam through a radiator to produce a bremsstrahlung photon beam and then passing the photon beam through a convertor to produce electron/positron pairs. The mixed electron-positron (lepton) beam with useful energies from approximately 0.85 to 3.5 GeV then struck a 30-cm long liquid hydrogen (LH$_2$) target located within the CEBAF Large Acceptance Spectrometer (CLAS). By detecting both the scattered leptons and the recoiling protons we identified and reconstructed elastic scattering events and determined the incident lepton energy. A detailed description of the experiment is presented., Comment: 21 pages, 22 figures

Published
2017

28. Target and beam-target spin asymmetries in exclusive pion electroproduction for Q2>1GeV2 . I. ep→eπ+n

Author

Sylvester Joosten, P. Lenisa, B. McKinnon, I. Zonta, G. Ciullo, C. Djalali, J. P. Ball, Y. Prok, D. S. Carman, M. Mirazita, V. Crede, Nikos Sparveris, X. Wei, M. Osipenko, N. Gevorgyan, V. Batourine, H. Egiyan, R. A. Badui, M. Guidal, S. Niccolai, R. A. Montgomery, S. E. Kuhn, M. Hattawy, Brian Raue, K. A. Griffioen, J. A. Fleming, A. Filippi, M. Holtrop, G. Charles, Gerard Gilfoyle, D. Protopopescu, D. Sokhan, L. Colaneri, A. Fradi, Andrew Puckett, E. Voutier, W. Kim, S. Chandavar, I. Bedlinskiy, P. Eugenio, M. Taiuti, Laura Clark, M. Khandaker, R. W. Gothe, P. Rossi, E. Seder, P. L. Cole, Z. W. Zhao, I. Stankovic, K. Livingston, Yordanka Ilieva, Iu. Skorodumina, S. Pisano, K. Hicks, P. Peng, M. J. Amaryan, L. Lanza, C. Munoz Camacho, M. E. McCracken, S. Strauch, G. Murdoch, S. M. Hughes, P. Nadel-Turonski, M. Ripani, L. A. Net, S. Stepanyan, W. Phelps, C. Gleason, Larry Weinstein, S. Koirala, N. K. Walford, F. X. Girod, A. El Alaoui, I. J. D. MacGregor, Andrea Celentano, B. Torayev, A. I. Ostrovidov, K. Park, M. Contalbrigo, Nicholas Zachariou, C. A. Meyer, D. G. Ireland, H. Jiang, G. V. Fedotov, Volker D. Burkert, A. S. Biselli, H. Hakobyan, M. Battaglieri, H. S. Jo, W. Gohn, Victor Mokeev, L. Elouadrhiri, I. I. Strakovsky, E. Fanchini, A. Deur, J. Zhang, J. W. Price, M. Ungaro, E. Golovatch, R. Dupre, K. Joo, E. L. Isupov, Ye Tian, R. De Vita, S. Anefalos Pereira, E. De Sanctis, R. A. Schumacher, T. A. Forest, N. A. Baltzell, G. Khachatryan, W. J. Briscoe, G. Rosner, Y. Ghandilyan, A. Kim, E. Munevar, B. S. Ishkhanov, George Davey Smith, A. D'Angelo, Frank Klein, L. El Fassi, P. E. Bosted, H. Avakian, H. Voskanyan, S. Bültmann, E. Pasyuk, V. P. Kubarovsky, and O. Pogorelko

Subjects
Physics, Meson, 010308 nuclear & particles physics, Scattering, Form factor (quantum field theory), Resonance, Electron, 01 natural sciences, Nuclear physics, Pion, 0103 physical sciences, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, Nucleon, Spin-½
Abstract

Beam-target double-spin asymmetries and target single-spin asymmetries were measured for the exclusive π 0 electroproduction reaction γ ∗ p → p π 0 , expanding an analysis of the γ ∗ p → n π + reaction from the same experiment. The results were obtained from scattering of 6-GeV longitudinally polarized electrons off longitudinally polarized protons using the CEBAF Large Acceptance Spectrometer at Jefferson Laboratory. The kinematic ranges covered are 1.1 < W < 3 GeV and 1 < Q 2 < 6 GeV 2 . Results were obtained for about 5700 bins in W , Q 2 , cos ( θ ∗ ) , and ϕ ∗ . The beam-target asymmetries were found to generally be greater than zero, with relatively modest ϕ ∗ dependence. The target asymmetries exhibit very strong ϕ ∗ dependence, with a change in sign occurring between results at low W and high W , in contrast to π + electroproduction. Reasonable agreement is found with phenomenological fits to previous data for W < 1.6 GeV, but significant differences are seen at higher W . When combined with cross-sectional measurements, as well as π + observables, the present results will provide powerful constraints on nucleon resonance amplitudes at moderate and large values of Q 2 , for resonances with masses as high as 2.4 GeV.

Published
2017

29. Exclusive η electroproduction at W>2 GeV with CLAS and transversity generalized parton distributions

Author

P. Eugenio, B. S. Ishkhanov, B. Torayev, C. E. Hyde, H. Hakobyan, R. De Vita, P. Nadel-Turonski, K. Livingston, I. Zonta, X. Wei, P. Stoler, W. Kim, S. Anefalos Pereira, G. Niculescu, A. Celentano, R. W. Gothe, R. A. Schumacher, K. L. Giovanetti, K. Hicks, Y. Prok, E. Golovatch, Nicholas M. Harrison, Gerard Gilfoyle, F. Sabatié, Larry Weinstein, D. G. Jenkins, G. Ciullo, J. P. Ball, R. Dupre, D. S. Carman, D. Sokhan, Eugene Pasyuk, E. De Sanctis, A. Ni, Laura Clark, L. Guo, R. G. Fersch, Alessandro Rizzo, K. P. Adhikari, T. A. Forest, N. A. Baltzell, E. Fanchini, P. L. Cole, G. Rosner, P. Lenisa, S. Stepanyan, K. A. Griffioen, A. Filippi, B. McKinnon, Igor Strakovsky, S. Niccolai, C. Hanretty, Dustin Keller, M. Osipenko, F. X. Girod, A. Movsisyan, A. El Alaoui, Y. Ilieva, Sergey Kuleshov, Nicholas Zachariou, A. D'Angelo, G. Charles, M. Khandaker, N. K. Walford, M. Mirazita, N. Dashyan, Y. Ghandilyan, P. Rossi, T. Cao, L. El Fassi, Michael Wood, Friedrich Klein, I. Bedlinskiy, J. Zhang, N. Gevorgyan, V. Batourine, I. J. D. MacGregor, Brian Raue, W. Phelps, E. L. Isupov, Ye Tian, M. Contalbrigo, V. Crede, H. Avakian, M. Ungaro, M. Taiuti, G. Khachatryan, H. Voskanyan, R. A. Montgomery, L. Colaneri, Iu. Skorodumina, S. Boiarinov, Z. Akbar, P. Roy, M. Turisini, P. Peng, C. Munoz Camacho, K. Joo, M. Guidal, H. S. Jo, N. Markov, A. Deur, S. Pisano, R. Paremuzyan, W. J. Briscoe, M. Yurov, G. D. Smith, J. W. Price, V. P. Kubarovsky, O. Pogorelko, S. M. Hughes, D. Protopopescu, A. I. Ostrovidov, K. Park, M. Garçon, E. Voutier, Victor Mokeev, D. G. Ireland, H. Jiang, C. Gleason, Z. E. Meziani, Volker D. Burkert, A. S. Biselli, C. Salgado, M. Hattawy, Michael Paolone, Chaden Djalali, Latifa Elouadrhiri, K. Hafidi, L. Lanza, M. Battaglieri, G. V. Fedotov, M. Ripani, S. Chandavar, Andrew Puckett, S. Strauch, M. Khachatryan, D. P. Watts, M. S. Saini, Nikolaos Sparveris, L. A. Net, Y. G. Sharabian, S. E. Kuhn, J. A. Fleming, A. Kim, and Sylvester Joosten

Subjects
Physics, Particle physics, Meson, 010308 nuclear & particles physics, Quark model, Structure function, Hadron, Sigma, Parton, Elementary particle, 01 natural sciences, 0103 physical sciences, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, Boson
Abstract

The cross section of the exclusive eta electroproduction reaction ep -> e'p'eta was measured at Jefferson Laboratorywith a 5.75 GeV electron beam and the CLAS detector. Differential cross sections d(4) sigma/dtdQ(2) dx(B)d phi(eta) and structure functions sigma(U) = sigma(T) + epsilon sigma(L), sigma(TT), and sigma(LT), as functions of t, were obtained over a wide range of Q(2) and x(B). The eta structure functions are compared with those previously measured for pi(0) at the same kinematics. At low t, both pi(0) and eta are described reasonably well by generalized parton distributions (GPDs) in which chiral-odd transversity GPDs are dominant. The pi(0) and eta data, when taken together, can facilitate the flavor decomposition of the transversity GPDs.

Published
2017

30. Beam-target double-spin asymmetry in quasielastic electron scattering off the deuteron with CLAS

Author

N. Compton, Chaden Djalali, R. A. Schumacher, F. X. Girod, R. Paremuzyan, S. Bültmann, Gerard Gilfoyle, T. A. Forest, C. D. Keith, I. Zonta, M. Osipenko, G. Khachatryan, Laura Clark, F. Sabatié, D. Sokhan, Marco Contalbrigo, S. Stepanyan, L. Guo, W. J. Briscoe, Avraham Klein, B. McKinnon, G. Asryan, C. Hanretty, S. Strauch, G. Charles, W. Kim, P. Rossi, R. A. Badui, M. Mirazita, G. Niculescu, J. W. Price, S. Niccolai, W. Phelps, P. Eugenio, V. Sytnik, Alessandro Rizzo, Victor Mokeev, G. Rosner, A. Deur, L. Lanza, M. Taiuti, L. Colaneri, M. Ungaro, W. K. Brooks, S. E. Kuhn, Y. Prok, Y. Ghandilyan, A. Celentano, R. W. Gothe, K. A. Griffioen, A. Kim, C. E. Hyde, B. S. Ishkhanov, J. A. Fleming, E. De Sanctis, V. Crede, J. P. Ball, M. H. Wood, R. Dupre, M. Battaglieri, Taya Chetry, D. S. Carman, Hrachya Hakobyan, B. Torayev, I. u. Skorodumina, I. Bedlinskiy, Z. Akbar, E. Fanchini, P. Bosted, K. Hicks, M. Guidal, R. De Vita, K. L. Giovanetti, A. I. Ostrovidov, K. Park, P. L. Cole, M. Holtrop, L. A. Net, E. Voutier, J. Zhang, Paolo Lenisa, D. G. Ireland, H. Jiang, A. Movsisyan, Volker D. Burkert, A. S. Biselli, H. Avakian, S. Anefalos Pereira, N. K. Walford, I. J. D. MacGregor, Latifa Elouadrhiri, George Davey Smith, G. V. Fedotov, Y. G. Sharabian, H. Voskanyan, D. G. Meekins, A. D'Angelo, Andrew Puckett, Martin K. Mayer, L. El Fassi, E. Pasyuk, M. Khachatryan, K. P. Adhikari, E. L. Isupov, N. A. Baltzell, Ye Tian, S. Boiarinov, Nikolaos Sparveris, C. Gleason, M. Ripani, V. P. Kubarovsky, O. Pogorelko, S. M. Hughes, N. Dashyan, Dustin Keller, I. Stankovic, Yordanka Ilieva, Giuseppe Ciullo, A. El Alaoui, Nicholas Zachariou, K. Livingston, M. Hattawy, R. Fersch, N. Guler, Larry Weinstein, A. Filippi, M. Khandaker, Old Dominion University [Norfolk] (ODU), Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), CLAS Collaboration, and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Particle physics, Nuclear and High Energy Physics, POLARIZED TARGET, media_common.quotation_subject, Hadron, Nuclear Theory, FOS: Physical sciences, Socio-culturale, Inelastic scattering, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, 01 natural sciences, Asymmetry, Settore FIS/04 - Fisica Nucleare e Subnucleare, Nuclear physics, Economica, 0103 physical sciences, Neutron, ELECTRODISINTEGRATION, Nuclear Experiment (nucl-ex), 010306 general physics, NUCLEON, Nuclear Experiment, QC, media_common, FORM-FACTOR, NEUTRON, STATE, Physics, 010308 nuclear & particles physics, Scattering, Momentum transfer, Quasielastic neutron scattering, Nucleon
Abstract

Quasi-elastic electron scattering on the deuteron is a benchmark reaction to test our understanding of deuteron structure and the properties and interactions of the two nucleons bound in the deuteron. The experimental data presented here can be used to test state-of-the-art models of the deuteron and the two-nucleon interaction in the final state after two-body breakup of the deuteron. Focusing on polarization degrees of freedom, we gain information on spin-momentum correlations in the deuteron ground state (due to the D-state admixture) and on the limits of the Impulse Approximation (IA) picture as it applies to measurements of spin-dependent observables like spin structure functions for bound nucleons. We measured the beam-target double spin asymmetry for quasi-elastic electron scattering off the deuteron at several beam energies using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. The deuterons were polarized along (or opposite to) the beam direction. The double spin asymmetries were measured as a function of photon virtuality , missing momentum, and the angle between the (inferred) "spectator" neutron and the momentum transfer direction. The results are compared with a recent model that includes Final State Interactions (FSI) using a complete parameterization of nucleon-nucleon scattering, as well as a simplified model using the Plane Wave Impulse Approximation (PWIA). We find overall good agreement with both the PWIA and FSI expectations at low to medium missing momenta, including the change of the asymmetry due to the contribution of the deuteron D-state at higher momenta. At the highest missing momenta, our data clearly agree better with the calculations including FSI., Comment: 19 pages, 17 figures, to be submitted to PRC

Published
2017

31. Hard exclusive pion electroproduction at backward angles with CLAS

Author

H. Avakian, B. S. Ishkhanov, K. A. Griffioen, H. Voskanyan, R. Paremuzyan, A. El Alaoui, E. L. Isupov, M. Battaglieri, Nicholas Zachariou, M. Ripani, I. Bedlinskiy, C. Salgado, K. Livingston, M. Hattawy, R. Fersch, S. Stepanyan, M. Ungaro, Nicholas M. Harrison, Gerard Gilfoyle, D. Sokhan, Laura Clark, P. Rossi, Maxime Defurne, Friedrich Klein, P. Eugenio, M. Taiuti, M. L. Kabir, G. Charles, F. Sabatié, A. D'Angelo, David M. Keller, L. Guo, D. Heddle, Chaden Djalali, I. J. D. MacGregor, R. W. Gothe, R. A. Schumacher, W. Kim, O. Pogorelko, F. X. Girod, L. Lanza, C. Munoz Camacho, J. W. Price, C. E. Hyde, C. Hanretty, X. Wei, Y. Prok, M. Khachatryan, K. Hicks, J. Ball, K. Hafidi, M. Osipenko, J. Zhang, D. Protopopescu, Latifa Elouadrhiri, R. De Vita, V. Crede, R. A. Montgomery, Nikolaos Sparveris, E. Voutier, S. Strauch, G. V. Fedotov, Y. G. Sharabian, M. Contalbrigo, Victor Mokeev, B. McKinnon, Taya Chetry, M. Khandaker, Iu. Skorodumina, Andrea Celentano, H. Hakobyan, L. El Fassi, M. Mirazita, J. Poudel, J. M. Laget, S. Niccolai, Z. Akbar, S. Johnston, N. Markov, Kirill M. Semenov-Tian-Shansky, I. I. Strakovsky, G. Niculescu, Y. Ilieva, K. P. Adhikari, A. Deur, E. De Sanctis, S. Adhikari, Y. Ghandilyan, A. Filippi, Michael Paolone, E. Golovatch, R. Dupre, P. L. Cole, D. G. Ireland, S. E. Kuhn, G. Ciullo, G. Khachatryan, D. S. Carman, F. Cao, A. Rizzo, M. Guidal, Volker D. Burkert, W. J. Briscoe, A. S. Biselli, E. Pasyuk, N. Dashyan, William Brooks, G. D. Smith, M. Holtrop, L. Barion, N. A. Baltzell, M. Garçon, H. Egiyan, P. Nadel-Turonski, K. Joo, J. A. Tan, D. G. Jenkins, Bernard Pire, W. Phelps, I. Balossino, K. Park, V. P. Kubarovsky, Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Centre de Physique Théorique [Palaiseau] (CPHT), École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Interactions Fondamentales en Physique et en Astrophysique (IFPA), Université de Liège, Thomas Jefferson National Accelerator Facility (Jefferson Lab), Istituto Nazionale di Fisica Nucleare, Sezione di Torino (INFN, Sezione di Torino), Istituto Nazionale di Fisica Nucleare (INFN), University of Ca’ Foscari [Venice, Italy], Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Clemson University, Old Dominion University [Norfolk] (ODU), CSIRO Astronomy and Space Science, Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), Massachusetts Institute of Technology (MIT), Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire d'automatique et de génie des procédés (LAGEP), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École Supérieure de Chimie Physique Électronique de Lyon (CPE)-Centre National de la Recherche Scientifique (CNRS), Politecnico di Torino = Polytechnic of Turin (Polito), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), School of Mechanical Engineering, University of Birmingham [Birmingham], School of Geography, Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Université de Lyon-Université de Lyon-École Supérieure Chimie Physique Électronique de Lyon-Centre National de la Recherche Scientifique (CNRS), and Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Quark, Nuclear and High Energy Physics, Electroproduction, Exclusive single pion, transition distribution amplitudes, Particle physics, Meson, Proton, Nuclear Theory, Hadron, Socio-culturale, FOS: Physical sciences, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], TDA, 01 natural sciences, Resonance (particle physics), CLAS, Eletroproduction, High Energy Physics - Experiment, Settore FIS/04 - Fisica Nucleare e Subnucleare, Nuclear Theory (nucl-th), High Energy Physics - Experiment (hep-ex), Pion, High Energy Physics - Phenomenology (hep-ph), 0103 physical sciences, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Experiment, Physics, 010308 nuclear & particles physics, lcsh:QC1-999, Baryon, High Energy Physics - Phenomenology, [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph], High Energy Physics::Experiment, Nucleon, lcsh:Physics
Abstract

We report on the first measurement of cross sections for exclusive deeply virtual pion electroproduction off the proton, $e p \to e^\prime n \pi^+$, above the resonance region at backward pion center-of-mass angles. The $\varphi^*_{\pi}$-dependent cross sections were measured, from which we extracted three combinations of structure functions of the proton. Our results are compatible with calculations based on nucleon-to-pion transition distribution amplitudes (TDAs) and shed new light on nucleon structure., Comment: 7 pages, 6figures

Published
2017
Full Text
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32. The HPS electromagnetic calorimeter

Author

M. Battaglieri, B. Raydo, Jeremy McCormick, L. Colaneri, R. Dupré, M. Bondì, I. Balossino, N. A. Baltzell, A. D'Angelo, M. Garçon, R. Paremuzyan, M. De Napoli, P. Rosier, A. Celentano, M. Ehrhart, A. Filippi, R. De Vita, N. Gevorgyan, V. P. Kubarovsky, G. Charles, S. Stepanyan, E. Rauly, Larry Weinstein, H. Szumila-Vance, E. Buchanan, A. Rizzo, Daniela Calvo, Valeria Sipala, M. Guidal, E. Rindel, M. Holtrop, N. Randazzo, M. Osipenko, B. McKinnon, K. Livingston, K. McCarty, F. X. Girod, Hovanes Egiyan, V. Iurasov, Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), HPS, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Istituto Nazionale di Fisica Nucleare, Sezione di Torino (INFN, Sezione di Torino), Istituto Nazionale di Fisica Nucleare (INFN), Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay ( IPNO ), Université Paris-Sud - Paris 11 ( UP11 ) -Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire AIM, and Université Paris Diderot - Paris 7 ( UPD7 ) -Centre d'Etudes de Saclay

Subjects
tungsten: oxygen, Photon, Physics - Instrumentation and Detectors, Physics::Instrumentation and Detectors, Elementary particle, Tracking (particle physics), 7. Clean energy, 01 natural sciences, Dark photon, Settore FIS/04 - Fisica Nucleare e Subnucleare, High Energy Physics - Experiment, 99-00, High Energy Physics - Experiment (hep-ex), [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Nuclear Experiment (nucl-ex), [ PHYS.NEXP ] Physics [physics]/Nuclear Experiment [nucl-ex], [ PHYS.PHYS.PHYS-INS-DET ] Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Instrumentation, Nuclear Experiment, Heavy photon, Electromagnetic calorimeter, Lead-tungstate crystals, Avalanche photodiodes, Physics, Detector, Nuclear and High Energy Physics, Instrumentation and Detectors (physics.ins-det), 00-01, Calorimeter, performance, Jefferson Lab, Author Keywords:Heavy photon, FOS: Physical sciences, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Linear particle accelerator, NO, Nuclear physics, [ PHYS.HEXP ] Physics [physics]/High Energy Physics - Experiment [hep-ex], 0103 physical sciences, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], 010306 general physics, lead, 010308 nuclear & particles physics, calorimeter: design, Avalanche photodiode, calorimeter: electromagnetic, photon: heavy, scintillation counter: crystal, High Energy Physics::Experiment
Abstract

The Heavy Photon Search experiment (HPS) is searching for a new gauge boson, the so-called "heavy photon." Through its kinetic mixing with the Standard Model photon, this particle could decay into an electron-positron pair. It would then be detectable as a narrow peak in the invariant mass spectrum of such pairs, or, depending on its lifetime, by a decay downstream of the production target. The HPS experiment is installed in Hall-B of Jefferson Lab. This article presents the design and performance of one of the two detectors of the experiment, the electromagnetic calorimeter, during the runs performed in 2015-2016. The calorimeter's main purpose is to provide a fast trigger and reduce the copious background from electromagnetic processes through matching with a tracking detector. The detector is a homogeneous calorimeter, made of 442 lead-tungstate (PbWO4) scintillating crystals, each read out by an avalanche photodiode coupled to a custom trans-impedance amplifier., 34 pages, 25 figures

Published
2017

33. Target and beam-target spin asymmetries in exclusive π+ and π− electroproduction with 1.6- to 5.7-GeV electrons

Author

N. Dashyan, Taya Chetry, I. Stankovic, Yordanka Ilieva, Sergey Kuleshov, C. Djalali, A. Filippi, H. Avakian, G. Charles, George Davey Smith, W. Gohn, N. A. Baltzell, D. G. Jenkins, I. I. Strakovsky, A. Deur, P. Bosted, P. Roy, D. Adikaram, F. X. Girod, R. A. Schumacher, S. Strauch, A. D'Angelo, B. McKinnon, E. Munevar, G. Niculescu, P. Eugenio, M. Taiuti, S. Joosten, M. Ungaro, D. Heddle, B. S. Ishkhanov, G. Ciullo, A. El Alaoui, Nicholas Zachariou, M. Holtrop, S. Bültmann, W. Kim, L. El Fassi, K. P. Adhikari, T. A. Forest, V. Crede, D. P. Watts, I. Zonta, S. Stepanyan, R. W. Gothe, Andrew Puckett, C. Gleason, J. Pierce, Avraham Klein, K. A. Griffioen, M. E. McCracken, P. Nadel-Turonski, E. Golovatch, R. Dupre, Carlos A. Salgado, K. Joo, M. Mirazita, B. Torayev, G. E. Dodge, H. Y. Lu, S. M. Hughes, K. Livingston, R. A. Badui, N. Gevorgyan, I. Bedlinskiy, H. S. Jo, A. Fradi, A. Simonyan, M. J. Amaryan, J. P. Ball, V. Sytnik, R. Fersch, D. S. Carman, M. Hattawy, M. Osipenko, N. Guler, Nikos Sparveris, P. Lenisa, W. J. Briscoe, I. Niculescu, X. Wei, E. Voutier, A. Movsisyan, S. L. Careccia, S. Niccolai, S. E. Kuhn, J. A. Fleming, V. P. Kubarovsky, S. Chandavar, V. Batourine, Victor Mokeev, A. Ni, D. Protopopescu, M. Garçon, A. Celentano, O. Pogorelko, Alessandro Rizzo, L. Lanza, Friedrich Klein, P. Rossi, K. L. Giovanetti, R. De Vita, E. Fanchini, E. Seder, P. Peng, Hovanes Egiyan, Larry Weinstein, C. Munoz Camacho, C. Hanretty, Brian Raue, M. Khandaker, M. Ripani, R. C. Minehart, S. Anefalos Pereira, C. A. Meyer, J. Zhang, R. Paremuzyan, H. Voskanyan, L. A. Net, G. V. Fedotov, J. W. Price, G. Rosner, S. Boiarinov, E. Pasyuk, Gerard Gilfoyle, Y. Ghandilyan, Dustin Keller, P. L. Cole, Z. W. Zhao, A. I. Ostrovidov, K. Park, Michael Wood, K. Hafidi, D. G. Ireland, H. Jiang, Y. G. Sharabian, Volker D. Burkert, X. Zheng, A. S. Biselli, L. Colaneri, N. Markov, S. Pisano, M. Battaglieri, S. Procureur, O. Cortes, E. L. Isupov, Ye Tian, Lorenzo Zana, L. Clark, K. Hicks, L. Guo, G. Asryan, N. Harrison, Iu. Skorodumina, W. Phelps, Y. Prok, F. Sabatié, M. Contalbrigo, Z. Akbar, N. K. Walford, T. Cao, and I. J. D. MacGregor

Subjects
Physics, Particle physics, 010308 nuclear & particles physics, Scattering, Resonance, Electron, Polarization (waves), Deep inelastic scattering, 01 natural sciences, Particle identification, Nuclear physics, Amplitude, 0103 physical sciences, Physics::Accelerator Physics, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, Nucleon
Abstract

Beam-target double spin asymmetries and target single-spin asymmetries in exclusive $\pi^+$ and $\pi^-$ electroproduction were obtained from scattering of 1.6 to 5.7 GeV longitudinally polarized electrons from longitudinally polarized protons (for $\pi^+$) and deuterons (for $\pi^-$) using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. The kinematic range covered is $1.1 1.5$ GeV. Very large target-spin asymmetries are observed for $W>1.6$ GeV. When combined with cross section measurements, the present results will provide powerful constraints on nucleon resonance amplitudes at moderate and large values of $Q^2$, for resonances with masses as high as 2.3 GeV.

Published
2016

34. Nucleon and nuclear structure through dilepton production

Author

M. Guidal, Z. W. Zhao, S. Stepanyan, O. V. Teryaev, V. Tadevosyan, S. Joosten, L. Szymanowski, C. E. Hyde, Kondo Gnanvo, W. C. Chang, Alexandre Camsonne, Kirill M. Semenov-Tian-Shansky, M. Boer, Vladimir M. Braun, O. Gryniuk, Marc Vanderhaeghen, Sean A Dobbs, Krešimir Kumerički, R. Boussarie, Zein-Eddine Meziani, Stanley J. Brodsky, L. Colaneri, A.V. Efremov, I. V. Anikin, P. Kroll, V. Guzey, N. A. Baltzell, Christian Weiss, E. Voutier, Yordanka Ilieva, Dario Müller, Jakub Wagner, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Drell-Yan process, generalized parton distribution, dimension: 3, Nuclear Theory, General Physics and Astronomy, parton: distribution function, Parton, 7. Clean energy, 01 natural sciences, transverse momentum: momentum spectrum, High Energy Physics - Phenomenology (hep-ph), 13.40.-f, star, 13.60.Fz, Nuclear Experiment (nucl-ex), nucleon structure, partons, Nuclear Experiment, Physics, Luminosity (scattering theory), Nuclear structure, nucleon, Drell–Yan process, imaging, PRIRODNE ZNANOSTI. Fizika, High Energy Physics - Phenomenology, partons, luminosity: high, Nucleon, Compton scattering, 13.60.Le, Particle physics, dilepton: production, conference summary, FOS: Physical sciences, Context (language use), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], nuclear physics, deeply virtual Compton scattering, 0103 physical sciences, quantum chromodynamics, structure, meson: production, 010306 general physics, 010308 nuclear & particles physics, Scattering, High Energy Physics::Phenomenology, nucleus, NATURAL SCIENCES. Physics, Automatic Keywords, nucleon structure, [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph], High Energy Physics::Experiment, hadron, acceptance
Abstract

Transverse momentum distributions and generalized parton distributions provide a comprehensive framework for the three-dimensional imaging of the nucleon and the nucleus experimentally using deeply virtual semi-exclusive and exclusive processes. The advent of combined high luminosity facilities and large acceptance detector capabilities enables experimental investigation of the partonic structure of hadrons with time-like virtual probes, in complement to the rich on-going space-like virtual probe program. The merits and benefits of the dilepton production channel for nuclear structure studies are discussed within the context of the International Workshop on Nucleon and Nuclear Structure through Dilepton Production taking place at the European Center for Theoretical Studies in Nuclear Physics and Related Areas (ECT$^{\star}$) of Trento. Particularly, the double deeply virtual Compton scattering, the time-like Compton scattering, the deeply virtual meson production, and the Drell-Yan processes are reviewed and a strategy for high impact experimental measurements is proposed., 21 pages, 23 figures, Conference proceedings

Published
2016

35. Measurement of target and double-spin asymmetries for the e⃗p⃗→eπ+(n) reaction in the nucleon resonance region at low Q2

Author

P. Roy, M. Guidal, V. Crede, S. Joosten, O. Pogorelko, Andrea Celentano, G. D. Smith, M. Holtrop, A. I. Ostrovidov, Paolo Rossi, Karl Slifer, D. G. Ireland, Andrew Puckett, R. A. Schumacher, Chaden Djalali, H. S. Jo, H. Jiang, Y. Ilieva, B. McKinnon, L. C. Smith, E. Munevar, I. Zonta, S. Strauch, Volker D. Burkert, A. S. Biselli, M. Osipenko, B. S. Ishkhanov, G. Ciullo, D. Keller, Nikolaos Sparveris, Taya Chetry, L. Colaneri, G. Khachatryan, Michael Paolone, P. Eugenio, M. Taiuti, S. Bültmann, Hyekoo Kang, L. El Fassi, P. Nadel-Turonski, H. Avakian, D. P. Watts, J. P. Ball, L. Clark, R. De Vita, A. Rizzo, M. Khandaker, D. G. Jenkins, X. Wei, M. Mirazita, A. Ni, S. Niccolai, L. Lanza, K. Hicks, R. W. Gothe, C. Salgado, M. J. Amaryan, N. Guler, A. Movsisyan, H. Egiyan, A. Filippi, G. Charles, Gerard Gilfoyle, I. I. Strakovsky, F. X. Girod, D. Adikaram, D. Sokhan, G. Murdoch, N. Markov, Seonho Choi, R. Paremuzyan, S. E. Kuhn, M. Battaglieri, K. Livingston, H. Voskanyan, E. Fanchini, K. L. Giovanetti, V. A. Drozdov, A. Deur, J. A. Fleming, J. P. Chen, E. Pasyuk, K. Kovacs, C. Gleason, G. E. Dodge, N. Gevorgyan, Larry Weinstein, C. Hanretty, W. Kim, W. J. Briscoe, F. Sabatié, E. De Sanctis, S. Pisano, S. K. Phillips, G. Niculescu, V. Batourine, S. Chandavar, N. A. Baltzell, R. Fersch, P. Bosted, E. Voutier, N. K. Walford, P. Lenisa, J. W. Price, P. Peng, L. Guo, M. Hattawy, I. Niculescu, G. Asryan, K. A. Griffioen, C. Munoz Camacho, I. Bedlinskiy, S. M. Hughes, E. N. Golovach, Victor Mokeev, P. L. Cole, N. Dashyan, K. Park, Iu. Skorodumina, R. Dupre, A. El Alaoui, I. Stankovic, R. A. Badui, I. J. D. MacGregor, M. Contalbrigo, Friedrich Klein, Brian Raue, Nicholas Zachariou, E. L. Isupov, G. V. Fedotov, N. Harrison, M. Ripani, L. A. Net, A. Kim, G. Rosner, N. Compton, Ye Tian, V. P. Kubarovsky, Annalisa D'Angelo, K. P. Adhikari, Z. Akbar, L. Elouadrhiri, S. Anefalos Pereira, Michael Wood, Y. G. Sharabian, Y. Ghandilyan, X. Zheng, J. Zhang, D. S. Carman, M. Ungaro, and E. Long

Subjects
Physics, Particle physics, 010308 nuclear & particles physics, Scattering, Cherenkov detector, media_common.quotation_subject, Electron, 01 natural sciences, Resonance (particle physics), Asymmetry, law.invention, Nuclear physics, law, 0103 physical sciences, Isobar, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, Nucleon, Spin-½, media_common
Abstract

We report measurements of target- and double-spin asymmetries for the exclusive channel $\vec e\vec p\to e\pi^+ (n)$ in the nucleon resonance region at Jefferson Lab using the CEBAF Large Acceptance Spectrometer (CLAS). These asymmetries were extracted from data obtained using a longitudinally polarized NH$_3$ target and a longitudinally polarized electron beam with energies 1.1, 1.3, 2.0, 2.3 and 3.0 GeV. The new results are consistent with previous CLAS publications but are extended to a low $Q^2$ range from $0.0065$ to $0.35$ (GeV$/c$)$^2$. The $Q^2$ access was made possible by a custom-built Cherenkov detector that allowed the detection of electrons for scattering angles as low as $6^\circ$. These results are compared with the unitary isobar models JANR and MAID, the partial-wave analysis prediction from SAID and the dynamic model DMT. In many kinematic regions our results, in particular results on the target asymmetry, help to constrain the polarization-dependent components of these models.

Published
2016

36. Photoproduction ofΛandΣ0hyperons using linearly polarized photons

Author

W. Kim, Michael Dugger, A. El Alaoui, Y. Ilieva, G. Niculescu, P. Peng, Hovanes Egiyan, C. Munoz Camacho, Nicholas Zachariou, R. A. Schumacher, D. G. Jenkins, V. P. Kubarovsky, A. I. Ostrovidov, K. Park, M. Contalbrigo, O. Pogorelko, S. M. Hughes, V. Crede, N. Compton, M. J. Amaryan, A. Ni, D. G. Ireland, H. Jiang, Dustin Keller, P. Lenisa, B. McKinnon, K. P. Adhikari, Volker D. Burkert, A. S. Biselli, J. A. Fleming, F. X. Girod, I. I. Strakovsky, I. Zonta, M. Taiuti, K. Hafidi, X. Wei, A. Deur, M. Osipenko, E. Munevar, Friedrich Klein, Iu. Skorodumina, Z. Akbar, M. Ungaro, Brian Raue, L. Clark, N. Gevorgyan, L. A. Net, H. Y. Lu, K. L. Giovanetti, W. K. Brooks, D. Protopopescu, R. A. Badui, P. Roy, C. Salgado, Y. G. Sharabian, C. Gleason, R. Paremuzyan, D. Adikaram, E. Voutier, H. Voskanyan, Andrew Puckett, J. W. Price, Barry Ritchie, W. J. Briscoe, R. Dupre, M. Hattawy, Gerard Gilfoyle, Nikolaos Sparveris, D. I. Glazier, A. Celentano, R. W. Gothe, A. Filippi, L. Guo, L. Colaneri, D. Sokhan, S. Niccolai, F. Sabatié, O. Cortes, E. L. Isupov, K. Livingston, G. D. Smith, M. Holtrop, M. Khandaker, S. Strauch, C. A. Paterson, Jie Zhang, N. Markov, R. De Vita, E. Seder, S. Pisano, G. V. Fedotov, P. Mattione, M. Ripani, D. P. Watts, K. Joo, N. K. Walford, G. Ciullo, J. P. Ball, Y. Prok, D. S. Carman, I. Bedlinskiy, S. Anefalos Pereira, Eugene Pasyuk, A. Rizzo, V. Sytnik, N. Harrison, I. J. D. MacGregor, A. Movsisyan, B. Torayev, E. Fanchini, K. A. Griffioen, Taya Chetry, D. I. Sober, Sergey Kuleshov, Victor Mokeev, P. Nadel-Turonski, K. Hicks, L. Lanza, C. Djalali, M. Battaglieri, M. E. McCracken, A. D'Angelo, G. Khachatryan, L. El Fassi, C. A. Mayer, R. Tucker, P. L. Cole, N. A. Baltzell, B. S. Ishkhanov, L. Zana, G. Rosner, and Y. Ghandilyan

Subjects
Physics, Quantum chromodynamics, Particle physics, Photon, 010308 nuclear & particles physics, Linear polarization, Bremsstrahlung, Strangeness, 01 natural sciences, Particle identification, Nuclear physics, Baryon, 0103 physical sciences, Nuclear Experiment, 010306 general physics, Nucleon
Abstract

Background: Measurements of polarization observables for the reactions (gamma) over right arrowp -> K+ Lambda and (gamma) over right arrowp -> K+ Sigma(0) have been performed. This is part of a program of measurements designed to study the spectrum of baryon resonances in particular, and nonperturbative QCD in general. Purpose: The accurate measurement of several polarization observables provides tight constraints for phenomenological fits, which allow the study of strangeness in nucleon and nuclear systems. Beam-recoil observables for the (gamma) over right arrowp -> K+ Sigma(0) reaction have not been reported before now. Method: Themeasurements were carried out using linearly polarized photon beams incident on a liquid hydrogen target, and the CLAS detector at the Thomas Jefferson National Accelerator Facility. The energy range of the results is 1.71 < W < 2.19 GeV, with an angular range -0.75 < cos theta(K)* < +0.85. Results: The observables extracted for both reactions are beam asymmetry Sigma, target asymmetry T, and the beam-recoil double polarization observables O-x and O-z. Conclusions: Comparison with theoretical fits indicates that, in the regions where no previous data existed, the new data contain significant new information, and strengthen the evidence for the set of resonances used in the latest Bonn-Gatchina fit.

Published
2016

37. First measurement of the helicity asymmetry E in η photoproduction on the proton

Author

K. A. Griffioen, K. Livingston, B. McKinnon, H. Hakobyan, C. Hanretty, S. Strauch, Latifa Elouadrhiri, C. A. Meyer, G. V. Fedotov, E. De Sanctis, I. Bedlinskiy, S. Chandavar, L. Colaneri, J. Brock, K. P. Adhikari, E. Golovatch, R. Dupre, D. I. Sober, M. C. Kunkel, V. Batourine, M. L. Seely, I. Zonta, Iu. Skorodumina, X. Wei, V. Crede, S. Pisano, Victor Mokeev, I. I. Strakovsky, E. Voutier, F. Sabatié, M. Ripani, D. I. Glazier, H. Egiyan, M. Ungaro, A. Deur, R. A. Montgomery, P. Stoler, Barry Ritchie, A. Simonyan, I. Senderovich, P. Lenisa, Z. W. Zhao, R. De Vita, Diane Schott, W. K. Brooks, A. El Alaoui, Y. Ilieva, K. Hicks, H. S. Jo, K. L. Giovanetti, Gerard Gilfoyle, K. Joo, C. D. Keith, Nicholas Zachariou, K. Park, N. K. Walford, D. G. Ireland, L. Guo, D. G. Jenkins, H. Jiang, Volker D. Burkert, A. S. Biselli, Sylvester Joosten, Michael Dugger, I. J. D. MacGregor, S. Anefalos Pereira, V. P. Kubarovsky, R. A. Badui, S. Park, N. Dashyan, A. Filippi, F. X. Girod, O. Pogorelko, S. M. Hughes, J. Zhang, W. Phelps, P. Nadel-Turonski, M. Khandaker, O. Cortes, W. Gohn, A. Celentano, R. W. Gothe, Ye Tian, Dustin Keller, Friedrich Klein, S. Boiarinov, D. G. Meekins, A. D'Angelo, J. W. Price, C. Djalali, Michael Wood, K. Hafidi, D. Rönchen, E. Seder, M. Contalbrigo, P. Mattione, P. Peng, L. El Fassi, C. Munoz Camacho, J. T. Goetz, R. Tucker, H. Voskanyan, P. L. Cole, E. Pasyuk, Z. Akbar, Lorenzo Zana, J. P. Ball, Y. Prok, P. Roy, D. Adikaram, M. Guidal, D. S. Carman, A. Rizzo, S. Niccolai, C. Salgado, G. D. Smith, M. Holtrop, A. Movsisyan, M. Battaglieri, S. Fegan, A. Kim, G. Charles, T. Mineeva, B. Morrison, V. Sytnik, P. Eugenio, B. S. Ishkhanov, R. A. Schumacher, P. Collins, B. Garillon, Michael Döring, D. Ho, S. Stepanyan, A. Fradi, H. Y. Lu, Andrew Puckett, Nikolaos Sparveris, I. Niculescu, J. A. Fleming, L. A. Net, C. Carlin, G. Rosner, M. Osipenko, Y. Ghandilyan, G. Khachatryan, W. J. Briscoe, G. Niculescu, M. Hattawy, N. A. Baltzell, Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), CLAS Collaboration, and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11)

Subjects
Particle physics, Nuclear and High Energy Physics, Meson, media_common.quotation_subject, Nuclear Theory, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Asymmetry, NO, Settore FIS/04 - Fisica Nucleare e Subnucleare, Nuclear physics, 0103 physical sciences, Eta photoproduction, ddc:530, Helicity asymmetry, Polarization observable, 010306 general physics, Nuclear Experiment, QC, media_common, Physics, Quantitative Biology::Biomolecules, 010308 nuclear & particles physics, Bremsstrahlung, Resonance, Observable, Helicity, lcsh:QC1-999, Baryon, Physics::Accelerator Physics, High Energy Physics::Experiment, Nucleon, lcsh:Physics
Abstract

Results are presented for the first measurement of the double-polarization helicity asymmetry E for the η photoproduction reaction γp→ηp. Data were obtained using the FROzen Spin Target (FROST) with the CLAS spectrometer in Hall B at Jefferson Lab, covering a range of center-of-mass energy W from threshold to 2.15 GeV and a large range in center-of-mass polar angle. As an initial application of these data, the results have been incorporated into the Jülich–Bonn model to examine the case for the existence of a narrow N⁎ resonance between 1.66 and 1.70 GeV. The addition of these data to the world database results in marked changes in the predictions for the E observable from that model. Further comparison with several theoretical approaches indicates these data will significantly enhance our understanding of nucleon resonances. Keywords: Eta photoproduction, Polarization observable, Helicity asymmetry

Published
2016

38. Moments of the spin structure functions g1p and g1d for 0.05<Q2<3.0 GeV2

Author

R. A. Schumacher, G. V. O'Rielly, C. D. Keith, Cynthia Marie Hadjidakis, Z. W. Zhao, Chaden Djalali, D. G. Jenkins, Michael Dugger, S. Tkachenko, H. O. Funsten, A. I. Ostrovidov, A. C S Lima, S. Bültmann, L. Morand, M. R. Niroula, T. A. Forest, D. G. Ireland, G. Asryan, Volker D. Burkert, A. S. Biselli, J. Pierce, Elton Smith, M. J. Amaryan, M. MacCormick, O. P. Dzyubak, R. A. Niyazov, I. Hleiqawi, S. L. Careccia, Larry Weinstein, Avraham Klein, E. Golovatch, H. G. Juengst, K. Moriya, Daniel S. Carman, J. Kuhn, Philip L. Cole, S. McAleer, H. Hakobyan, S. Anefalos Pereira, P. D. Rubin, L. Blaszczyk, P. Corvisiero, Y. G. Sharabian, A. Fradi, L. Cheng, G. Audit, A.V. Stavinsky, C. E. Hyde-Wright, F. Sabatié, Nikolay Shvedunov, D. Heddle, P. Stoler, Friedrich Klein, J. P. Cummings, R. De Vita, N. Markov, V. Sapunenko, C. Salgado, Dinko Pocanic, L. Elouadrhiri, N. Kalantarians, S. Stepanyan, K. S. Egiyan, R. C. Minehart, C. A. Meyer, J. Ball, M. Taiuti, S. E. Kuhn, I. I. Strakovsky, M. Bektasoglu, M. Kossov, K. Mikhailov, K.H. Hicks, R. J. Feuerbach, G. V. Fedotov, M. Nozar, A. Deur, I. Popa, V. Crede, J. W. Price, Shifeng Chen, M. Anghinolfi, Laird Kramer, D. P. Watts, H. Egiyan, G. Gavalian, John A. Mueller, L. Casey, B. L. Berman, P. Mattione, B. B. Niczyporuk, G. Rosner, N. Benmouna, N. Pivnyuk, Kwangsoo Kim, J. T. Goetz, M. Mirazita, G. Riccardi, J. R. Calarco, R. A. Miskimen, B. A. Raue, B. McKinnon, W. J. Briscoe, L. M. Qin, R. G. Fersh, P. Eugenio, J. Langheinrich, C. Butuceanu, C. Hanretty, S. S. Stepanyan, E. Pasyuk, S. A. Philips, M. Ripani, G. Ricco, S. A. Morrow, C. Paterson, Y. Ilieva, Michael Vineyard, Victor Mokeev, M. Klusman, B. M. Preedom, D. Branford, P. Collins, B. Moreno, J. R. Johnstone, Lorenzo Zana, J. P. Santoro, Tsutomu Mibe, Gerald Feldman, J. M. Laget, L. Todor, D. Protopopescu, K. L. Giovanetti, S. V. Kuleshov, C. Marchand, S. Pozdniakov, M. Garçon, M. L. Seely, Ji Li, D. J. Tedeschi, G. E. Dodge, H. Y. Lu, J. Lachniet, I. Bedlinskiy, Marco A. Huertas, A. Tkabladze, M. D. Mestayer, E. L. Isupov, P. V. Degtyarenko, D. Rowntree, K. Livingston, Michael L. Williams, M. Holtrop, R. Suleiman, V. Kuznetsov, D. S. Dale, J. Zhang, S. Boiarinov, D. I. Sober, Gerard Gilfoyle, F. X. Girod, G. S. Mutchler, N. A. Baltzell, I. Niculescu, D. Sokhan, J. Salamanca, K. A. Griffioen, D. Lawrence, M. Guillo, N. Guler, R. De Masi, L. El Fassi, J. W C McNabb, Sylvain Bouchigny, H. Denizli, M. Guidal, M. Battaglieri, J. Hardie, S. Strauch, J. D. Kellie, Z. Krahn, R. Nasseripour, S. Barrow, P. Rossi, R. Dickson, N. Baillie, D. Doughty, V. Gyurjyan, R. Bradford, K. Lukashin, B. E. Stokes, G. S. Adams, H. Bagdasaryan, P. Nadel-Turonski, A. V. Skabelin, K. Joo, A. Cazes, S. Procureur, Maryam Moteabbed, Bernhard Mecking, K. V. Dharmawardane, L. Guo, M. Ungaro, D. P. Weygand, E. Wolin, N. Hassall, M. Bellis, D. G. Crabb, J. Yun, D. Cords, P. Bosted, A. Yegneswaran, N. Dashyan, Y. Prok, Barry Ritchie, E. De Sanctis, H. S. Jo, S. Niccolai, R. Fatemi, A. V. Vlassov, P. Coltharp, R. W. Gothe, M. M. Ito, K. Y. Kim, M. Osipenko, K. Beard, L. C. Smith, E. Munevar, Kalvir S. Dhuga, B. S. Ishkhanov, O. Pogorelko, M. Khandaker, B. Zhao, F. W. Hersman, W. Kim, G. Niculescu, N. Gevorgyan, L. C. Dennis, B. E. Bonner, H. Avakian, D. Sharov, S. A. Dytman, W. K. Brooks, K. Park, V. P. Kubarovsky, J. Shaw, Michael Wood, K. Hafidi, and V. S. Serov

Subjects
Physics, Nuclear and High Energy Physics, Chiral perturbation theory, Heavy baryon chiral perturbation theory, Proton, 010308 nuclear & particles physics, Nuclear Theory, Hadron, 01 natural sciences, Baryon, Nuclear physics, Polarizability, 0103 physical sciences, Sum rule in quantum mechanics, Nuclear Experiment, 010306 general physics, Nucleon
Abstract

The spin structure functions g 1 for the proton and the deuteron have been measured over a wide kinematic range in x and Q 2 using 1.6 and 5.7 GeV longitudinally polarized electrons incident upon polarized NH3 and ND3 targets at Jefferson Lab. Scattered electrons were detected in the CEBAF Large Acceptance Spectrometer, for 0.05 Q 2 5 GeV 2 and W 3 GeV . The first moments of g 1 for the proton and deuteron are presented – both have a negative slope at low Q 2 , as predicted by the extended Gerasimov–Drell–Hearn sum rule. The first extraction of the generalized forward spin polarizability of the proton γ 0 p is also reported. This quantity shows strong Q 2 dependence at low Q 2 . Our analysis of the Q 2 evolution of the first moment of g 1 shows agreement in leading order with Heavy Baryon Chiral Perturbation Theory. However, a significant discrepancy is observed between the γ 0 p data and Chiral Perturbation calculations for γ 0 p , even at the lowest Q 2 .

Published
2009

39. Exclusive ρ0 electroproduction on the proton at CLAS

Author

J. Langheinrich, S. S. Stepanyan, E. Pasyuk, S. A. Philips, N. Dashyan, V. Sapunenko, G. Ricco, Alexei V. Klimenko, N. A. Baltzell, C. Salgado, Dinko Pocanic, Barry Ritchie, H. Denizli, A. V. Skabelin, K. A. Griffioen, B. Zhao, V. Gyurjyan, A. I. Ostrovidov, R. Fatemi, K. Park, S. E. Kuhn, Latifa Elouadrhiri, R. C. Minehart, Kei Moriya, C. A. Meyer, H. G. Juengst, B. E. Stokes, G. S. Adams, G. V. Fedotov, V. P. Kubarovsky, J. Zhang, P. Eugenio, K. P. Adhikari, A. V. Vlassov, D. P. Weygand, G. E. Dodge, H. Y. Lu, M. J. Amaryan, G. V. O'Rielly, S. Niccolai, Z. W. Zhao, V. Mokeev, Y. Ilieva, Ji Li, D. G. Jenkins, C. Tur, Gerard Gilfoyle, Elton Smith, H. Hakobyan, A.V. Stavinsky, J. D. Kellie, M. Guidal, M. MacCormick, I. Hleiqawi, S. L. Careccia, R. De Vita, Friedrich Klein, Brian Raue, P. V. Degtyarenko, M. D. Mestayer, J. P. Didelez, R. Nasseripour, L. Todor, F. W. Hersman, P. Coltharp, E. L. Isupov, J. P. Cummings, W. Gohn, S. A. Morrow, S. McAleer, M. Anghinolfi, P. Nadel-Turonski, D. Sokhan, D. Protopopescu, D. J. Tedeschi, M. Holtrop, Michael L. Williams, P. Collins, K. L. Giovanetti, I. Niculescu, F. X. Girod, L. Blaszczyk, B. Carnahan, James Mueller, D. Lawrence, R. G. Fersch, R. A. Miskimen, B. McKinnon, S. Pozdniakov, M. Garçon, J. J. Melone, M. M. Ito, S. Boiarinov, Larry Weinstein, L. Zana, P. D. Rubin, R. De Masi, D. Keller, I. Bedlinskiy, B. M. Preedom, S. Anefalos Pereira, D. Schott, Y. G. Sharabian, R. A. Schumacher, P. L. Cole, M. Yurov, M. Taiuti, S. Mehrabyan, D. Branford, L. C. Smith, E. Munevar, G. S. Mutchler, B. S. Ishkhanov, Michael Wood, K. Hafidi, L. Graham, M. Kossov, M. E. McCracken, C. I O Gordon, J. M. Laget, V. Kuznetsov, J. Kuhn, E. Hourany, M. Khandaker, V. S. Serov, L. C. Dennis, B. E. Bonner, J. W. Price, Tsutomu Mibe, S. Bültmann, G. Audit, Shifeng Chen, C. Bookwalter, N. Gevorgyan, M. Osipenko, C. E. Hyde-Wright, J. P. Santoro, H. S. Jo, H. Avakian, L. Morand, I. Popa, D. Sharov, T. A. Forest, G. Riccardi, M. R. Niroula, E. De Sanctis, O. Pogorelko, S. Stepanyan, P. Mattione, C. Butuceanu, M. S. Saini, D. Doughty, J. Pierce, M. Ripani, B. L. Berman, Avraham Klein, L. M. Qin, M. Aghasyan, E. Wolin, Sergey Kuleshov, W. J. Briscoe, D. Heddle, J. T. Goetz, D. I. Sober, Kalvir S. Dhuga, M. Bektasoglu, S. A. Dytman, S. Dhamija, M. Nozar, E. Polli, M. Mirazita, C. Paterson, J. P. Ball, R. W. Gothe, Y. Prok, B. Moreno, W. Kim, J. Hardie, Hall Crannell, D. S. Carman, K. Livingston, G. Rosner, C. Marchand, G. Niculescu, D. S. Dale, N. Baillie, S. Park, Sylvain Bouchigny, J. Lachniet, A. Tkabladze, D. G. Crabb, R. Dickson, Michael Vineyard, D. G. Ireland, V. Crede, J. R. Calarco, P. Khetarpal, N. Guler, J. Salamanca, L. El Fassi, J. W C McNabb, S. Barrow, P. Rossi, L. Casey, H. Bagdasaryan, Volker D. Burkert, A. S. Biselli, B. B. Niczyporuk, N. Pivnyuk, P. Stoler, C. Hanretty, Laird Kramer, J. R. Johnstone, L. Guo, M. Ungaro, A. Fradi, K. Joo, D. Cords, N. Markov, A. Yegneswaran, K. Hicks, M. Battaglieri, R. Bradford, K. S. Egiyan, A. Cazes, S. Procureur, Maryam Moteabbed, Bernhard Mecking, K. V. Dharmawardane, N. Hassall, M. Bellis, K. Mikhailov, G. Asryan, O. P. Dzyubak, R. A. Niyazov, P. Corvisiero, S. Strauch, D. P. Watts, H. Egiyan, I. I. Strakovsky, A. Deur, W. K. Brooks, R. J. Feuerbach, Cynthia Marie Hadjidakis, M. Guillo, Chaden Djalali, Michael Dugger, L. Cheng, F. Sabatié, Nikolay Shvedunov, N. Kalantarians, G. Gavalian, S. Tkachenko, and N. Benmouna

Subjects
Quark, Physics, REPRESENTATION, Nuclear and High Energy Physics, Particle physics, Valence (chemistry), Proton, Hadron, Parton, VECTOR-MESON ELECTROPRODUCTION, Approx, PHOTONS, QCD, EVOLUTION, High Energy Physics - Experiment, Regge theory, Nuclear physics, Scattering amplitude, GENERALIZED PARTON DISTRIBUTIONS, VIRTUAL COMPTON-SCATTERING, VECTOR-MESON ELECTROPRODUCTION, LARGE MOMENTUM-TRANSFER, DIFFRACTIVE PRODUCTION, PHOTOPRODUCTION, PHOTONS, QCD, REPRESENTATION, EVOLUTION, LARGE MOMENTUM-TRANSFER, GENERALIZED PARTON DISTRIBUTIONS, DIFFRACTIVE PRODUCTION, PHOTOPRODUCTION, Nuclear Experiment, VIRTUAL COMPTON-SCATTERING
Abstract

The $e p\to e^\prime p \rho^0$ reaction has been measured, using the 5.754 GeV electron beam of Jefferson Lab and the CLAS detector. This represents the largest ever set of data for this reaction in the valence region. Integrated and differential cross sections are presented. The $W$, $Q^2$ and $t$ dependences of the cross section are compared to theoretical calculations based on $t$-channel meson-exchange Regge theory on the one hand and on quark handbag diagrams related to Generalized Parton Distributions (GPDs) on the other hand. The Regge approach can describe at the $\approx$ 30% level most of the features of the present data while the two GPD calculations that are presented in this article which succesfully reproduce the high energy data strongly underestimate the present data. The question is then raised whether this discrepancy originates from an incomplete or inexact way of modelling the GPDs or the associated hard scattering amplitude or whether the GPD formalism is simply inapplicable in this region due to higher-twists contributions, incalculable at present., Comment: 29 pages, 29 figures

Published
2008

40. Cross Sections for the Exclusive Photon Electroproduction on the Proton and Generalized Parton Distributions

Author

H S, Jo, F X, Girod, H, Avakian, V D, Burkert, M, Garçon, M, Guidal, V, Kubarovsky, S, Niccolai, P, Stoler, K P, Adhikari, D, Adikaram, M J, Amaryan, M D, Anderson, S, Anefalos Pereira, J, Ball, N A, Baltzell, M, Battaglieri, V, Batourine, I, Bedlinskiy, A S, Biselli, S, Boiarinov, W J, Briscoe, W K, Brooks, D S, Carman, A, Celentano, S, Chandavar, G, Charles, L, Colaneri, P L, Cole, N, Compton, M, Contalbrigo, V, Crede, A, D'Angelo, N, Dashyan, R, De Vita, E, De Sanctis, A, Deur, C, Djalali, R, Dupre, A El, Alaoui, L El, Fassi, L, Elouadrhiri, G, Fedotov, S, Fegan, A, Filippi, J A, Fleming, B, Garillon, N, Gevorgyan, Y, Ghandilyan, G P, Gilfoyle, K L, Giovanetti, J T, Goetz, E, Golovatch, R W, Gothe, K A, Griffioen, B, Guegan, N, Guler, L, Guo, K, Hafidi, H, Hakobyan, N, Harrison, M, Hattawy, K, Hicks, N, Hirlinger Saylor, D, Ho, M, Holtrop, S M, Hughes, Y, Ilieva, D G, Ireland, B S, Ishkhanov, D, Jenkins, K, Joo, S, Joosten, D, Keller, G, Khachatryan, M, Khandaker, A, Kim, W, Kim, A, Klein, F J, Klein, S E, Kuhn, S V, Kuleshov, P, Lenisa, K, Livingston, H Y, Lu, I J D, MacGregor, B, McKinnon, Z E, Meziani, M, Mirazita, V, Mokeev, R A, Montgomery, H, Moutarde, A, Movsisyan, E, Munevar, C, Munoz Camacho, P, Nadel-Turonski, L A, Net, G, Niculescu, M, Osipenko, A I, Ostrovidov, M, Paolone, K, Park, E, Pasyuk, J J, Phillips, S, Pisano, O, Pogorelko, J W, Price, S, Procureur, Y, Prok, A J R, Puckett, B A, Raue, M, Ripani, A, Rizzo, G, Rosner, P, Rossi, P, Roy, F, Sabatié, C, Salgado, D, Schott, R A, Schumacher, E, Seder, A, Simonyan, Iu, Skorodumina, G D, Smith, D, Sokhan, N, Sparveris, S, Stepanyan, I I, Strakovsky, S, Strauch, V, Sytnik, Ye, Tian, S, Tkachenko, M, Ungaro, H, Voskanyan, E, Voutier, N K, Walford, D P, Watts, X, Wei, L B, Weinstein, M H, Wood, N, Zachariou, L, Zana, J, Zhang, Z W, Zhao, I, Zonta, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Thomas Jefferson National Accelerator Facility (Jefferson Lab), Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Rensselaer Polytechnic Institute (RPI), Old Dominion University [Norfolk] (ODU), Argonne National Laboratory [Lemont] (ANL), Universidad Tecnica Federico Santa Maria [Valparaiso] (UTFSM), University of Connecticut (UCONN), Ohio University, Carnegie Mellon University [Pittsburgh] (CMU), CLAS Collaboration, and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Particle physics, Photon, Proton, HERA, General Physics and Astronomy, Socio-culturale, FOS: Physical sciences, Parton, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], High Energy Physics - Experiment, Settore FIS/04 - Fisica Nucleare e Subnucleare, Nuclear physics, High Energy Physics - Experiment (hep-ex), CLAS, virtual compton scattering, Twist, Nuclear Experiment (nucl-ex), VIRTUAL COMPTON-SCATTERING, NUCLEON, Nuclear Experiment, Quantum chromodynamics, Physics, 3. Good health, Phase space, virtual compton scattering, nucleon, High Energy Physics::Experiment, Nucleon
Abstract

Unpolarized and beam-polarized four-fold cross sections $\frac{d^4 \sigma}{dQ^2 dx_B dt d\phi}$ for the $ep\to e^\prime p^\prime \gamma$ reaction were measured using the CLAS detector and the 5.75-GeV polarized electron beam of the Jefferson Lab accelerator, for 110 ($Q^2,x_B,t$) bins over the widest phase space ever explored in the valence-quark region. Several models of Generalized Parton Distributions (GPDs) describe the data well at most of our kinematics. This increases our confidence that we understand the GPD $H$, expected to be the dominant contributor to these observables. Through a leading-twist extraction of Compton Form Factors, these results reveal a tomographic image of the nucleon., Comment: 7 pages, 5 figures

Published
2015

41. Measurement of the x- and Q2-dependence of the asymmetry A1 on the nucleon

Author

L. Elouadrhiri, R. A. Miskimen, M. Khandaker, B. McKinnon, G. Rosner, I. I. Strakovsky, R. W. Gothe, M. Bellis, D. Branford, P. Rossi, K. Y. Kim, A. Deur, S. V. Kuleshov, H. G. Juengst, K. S. Egiyan, P. V. Degtyarenko, P. Dragovitsch, M. Battaglieri, M. Nozar, D. J. Tedeschi, M. Taiuti, I. Bedlinskiy, L. Todor, J. P. Cummings, D. Doughty, F. X. Girod, S. Niccolai, D. Protopopescu, Laird Kramer, J. Hardie, V. Gyurjyan, R. De Masi, B. E. Stokes, F. Ronchetti, R. A. Schumacher, P. Corvisiero, V. P. Kubarovsky, G. S. Adams, D. Heddle, Brian Raue, M. Mirazita, G. Ricco, Dinko Pocanic, L. C. Smith, S. Tkachenko, R. Bradford, K. Lukashin, Y. G. Sharabian, O. Pogorelko, E. Wolin, S. McAleer, S. E. Kuhn, V. Sapunenko, B. S. Ishkhanov, Ji Li, Jean Laget, N. Benmouna, N. Pivnyuk, Rakhsha Nasseripour, B. Carnahan, L. C. Dennis, B. E. Bonner, M. Guillo, C. Tur, J. Napolitano, A. I. Ostrovidov, R. Fatemi, A. C S Lima, Gerard Gilfoyle, D. Cords, Marco A. Huertas, H. Avakian, E. S. Smith, K. Park, A. V. Vlassov, D. G. Ireland, M. R. Niroula, V. Batourine, B. Zhao, Y. Ilieva, E. L. Isupov, R. Suleiman, I. Hleiqawi, L. Guo, S. Bültmann, Volker D. Burkert, A. S. Biselli, H. S. Jo, E. Golovatch, Michael L. Williams, P. Bosted, S. L. Careccia, James Mueller, G. S. Mutchler, R. DeVita, M. Ripani, S. A. Morrow, Atilla Gonenc, M. MacCormick, C. Djalali, F. W. Hersman, T. A. Forest, M. Anghinolfi, P. D. Rubin, S. Stepanyan, A. Cazes, G. Gavalian, J. W. Price, S. Boiarinov, Maryam Moteabbed, B. M. Preedom, N. A. Baltzell, Sylvain Bouchigny, J. P. Ball, Y. Prok, K. L. Giovanetti, Michael Dugger, A. Yegneswaran, Shifeng Chen, K. V. Dharmawardane, J. Pierce, M. Kossov, Avraham Klein, Jens H. Kuhn, A. Stavinsky, Larry Weinstein, P. Ambrozewicz, E. Pasyuk, L. M. Qin, K. A. Griffioen, H. O. Funsten, P. Coltharp, U. Thoma, C. Keith, Lorenzo Zana, D. P. Weygand, S. A. Dytman, Hall Crannell, M. M. Ito, N. Baillie, J. T. Goetz, G. V. O'Rielly, C. Paterson, M. Klusman, K. Livingston, V. Crede, Z. W. Zhao, Frank Klein, D. G. Crabb, J. R. Calarco, S. Strauch, D. G. Jenkins, C. Salgado, J. D. Kellie, G. E. Dodge, S. Pozdniakov, N. Guler, J. W C McNabb, M. D. Mestayer, I. Niculescu, Nikolay Shvedunov, D. Lawrence, M. Guidal, D. I. Sober, S. S. Stepanyan, M. Osipenko, S. Barrow, F. Sabatié, Michael Vineyard, K. Beard, M. Garçon, B. Mecking, G. Riccardi, J. Shaw, C. Butuceanu, Michael Wood, W. K. Brooks, K. Hafidi, V. S. Serov, Victor Mokeev, M. Ungaro, K. Joo, J. Yun, J. P. Santoro, Roy Thompson, K. Kim, J. J. Manak, P. Eugenio, J. Zhang, H. Bagdasaryan, P. Collins, Daniel S. Carman, C. Hadjidakis, C. E. Hyde-Wright, M. Bektasoglu, J. Langheinrich, S. A. Philips, G. Niculescu, M. Holtrop, Hong Lu, P. L. Cole, P. Nadel-Turonski, Tsutomu Mibe, B. B. Niczyporuk, J. Lachniet, A. Tkabladze, D. Rowntree, R. S. Hakobyan, J. Donnelly, O. P. Dzyubak, R. A. Niyazov, R. J. Feuerbach, L. Morand, P. Stoler, E. De Sanctis, K. Hicks, W. Kim, Susan Taylor, K. Mikhailov, H. Egiyan, N. Markov, Barry Ritchie, G. Asryan, H. Denizli, A. V. Skabelin, R. C. Minehart, C. A. Meyer, G. V. Fedotov, and E. Polli

Subjects
Quark, Physics, Nuclear and High Energy Physics, Particle physics, Proton, 010308 nuclear & particles physics, media_common.quotation_subject, Momentum transfer, Quark model, Parton, 01 natural sciences, Asymmetry, Nuclear physics, 0103 physical sciences, Invariant mass, 010306 general physics, Nucleon, media_common
Abstract

We report results for the virtual photon asymmetry A{sub 1} on the nucleon from new Jefferson Lab measurements. The experiment, which used the CEBAF Large Acceptance Spectrometer and longitudinally polarized proton ({sup 15}NH{sub 3}) and deuteron ({sup 15}ND{sub 3}) targets, collected data with a longitudinally polarized electron beam at energies between 1.6 GeV and 5.7 GeV. In the present paper, we concentrate on our results for A{sub 1}(x,Q{sup 2}) and the related ratio g{sub 1}/F{sub 1}(x,Q{sup 2}) in the resonance and the deep inelastic regions for our lowest and highest beam energies, covering a range in momentum transfer Q{sup 2} from 0.05 to 5.0 GeV{sup 2} and in final-state invariant mass W up to about 3 GeV. Our data show detailed structure in the resonance region, which leads to a strong Q{sup 2}--dependence of A{sub 1}(x,Q{sup 2}) for W below 2 GeV. At higher W, a smooth approach to the scaling limit, established by earlier experiments, can be seen, but A{sub 1}(x,Q{sup 2}) is not strictly Q{sup 2}--independent. We add significantly to the world data set at high x, up to x = 0.6. Our data exceed the SU(6)-symmetric quark model expectation for both the proton and the deuteron whilemore » being consistent with a negative d-quark polarization up to our highest x. This data set should improve next-to-leading order (NLO) pQCD fits of the parton polarization distributions.« less

Published
2006

42. Publisher's Note: Exclusiveπ0electroproduction atW>2GeV with CLAS [Phys. Rev. C 90, 025205 (2014)]

Author

George Davey Smith, N. A. Baltzell, D. Doughty, M. Khandaker, A. Simonyan, J. P. Ball, A. D'Angelo, Y. Prok, D. S. Carman, I. Zonta, H. Moutarde, K. L. Giovanetti, Larry Weinstein, X. Wei, H. Y. Lu, E. De Sanctis, V. P. Kubarovsky, M. Contalbrigo, Sergey Kuleshov, L. El Fassi, O. Pogorelko, D. I. Sober, D. Protopopescu, M. Garçon, E. Voutier, A. Movsisyan, N. Dashyan, Y. G. Sharabian, S. Chandavar, Frank Klein, A. V. Vlassov, F. X. Girod, D. G. Ireland, Dustin Keller, K. Livingston, C. Munoz Camacho, R. De Vita, K. P. Adhikari, V. Crede, Andrew Puckett, Lorenzo Zana, Martin K. Mayer, K. Hafidi, R. Dupre, S. Anefalos Pereira, V. Sytnik, M. Battaglieri, P. L. Cole, Z. W. Zhao, H. Hakobyan, H. S. Jo, B. McKinnon, S. Strauch, W. Kim, S. Niccolai, H. Avakian, P. Nadel-Turonski, B. Guegan, R. A. Montgomery, M. Mirazita, I. Niculescu, M. Yurov, E. Phelps, Diane Schott, H. Voskanyan, N. Gevorgyan, S. Fegan, S. Koirala, A. I. Ostrovidov, K. Park, G. V. Fedotov, W. J. Briscoe, E. Pasyuk, P. Roy, C. Djalali, A. Celentano, R. W. Gothe, M. Ripani, Volker D. Burkert, M. Guidal, A. S. Biselli, D. P. Watts, H. Egiyan, Nicholas M. Harrison, A. El Alaoui, L. Colaneri, Gerard Gilfoyle, D. Sokhan, D. G. Jenkins, W. I. Levine, M. Holtrop, Nicholas Zachariou, N. Markov, R. A. Schumacher, S. E. Kuhn, M. Hattawy, S. Pisano, Luciano Pappalardo, O. Cortes, I. Bedlinskiy, J. A. Fleming, J. Bono, K. A. Griffioen, E. L. Isupov, N. K. Walford, Andreas Klein, J. J. Phillips, Ye Tian, S. Park, P. Eugenio, Carlos A. Salgado, S. Boiarinov, P. Rossi, W. Tang, Y. Ghandilyan, Barry Ritchie, B. S. Ishkhanov, M. Osipenko, T. A. Forest, S. Stepanyan, B. Garillon, S. Procureur, P. Stoler, A. Kim, E. Seder, K. Hicks, William Brooks, I. J. D. MacGregor, W. Phelps, G. Gavalian, V. Mokeev, I. Senderovich, Alessandro Rizzo, E. Golovatch, L. Elouadrhiri, A. Deur, J. Zhang, J. W. Price, L. Guo, M. Ungaro, K. Joo, V. Batourine, F. Sabatié, C. I. Moody, P. Lenisa, and Brian Raue

Subjects
Physics, Nuclear physics, Nuclear and High Energy Physics, Meson production
Published
2014

43. Precision measurements ofg1of the proton and of the deuteron with 6 GeV electrons

Author

P. Lenisa, N. A. Baltzell, D. Meekins, E. De Sanctis, M. Aghasyan, C. Keith, D. I. Sober, Friedrich Klein, K. A. Griffioen, G. Rosner, M. Contalbrigo, L. Elouadrhiri, V. Crede, O. Pogorelko, Y. Ghandilyan, F. Sabatié, P. Roy, C. Smith, Diane Schott, Victor Mokeev, C. Hanretty, D. S. Carman, R. A. Montgomery, M. J. Amaryan, D. Adikaram, A. I. Ostrovidov, K. Park, K. Hicks, J. W. Price, S. Strauch, S. Fegan, H. S. Jo, H. Moutarde, S. Tkachenko, A. V. Vlassov, D. G. Ireland, G. D. Smith, S. Stepanyan, M. Holtrop, D. Protopopescu, K. Joo, W. Tang, A. Movsisyan, E. Voutier, T. Mineeva, K. L. Giovanetti, Larry Weinstein, B. Zhao, S. Pozdniakov, M. Garçon, Nicholas Kvaltine, R. A. Schumacher, I. Zonta, P. Bosted, N. Harrison, Volker D. Burkert, A. S. Biselli, S. Koirala, M. Osipenko, A. Kim, B. Guegan, S. S. Jawalkar, J. J. Phillips, R. De Vita, M. Ungaro, J. Brock, S. Anefalos Pereira, H. Voskanyan, Y. Prok, W. Gohn, S. Bültmann, K. Hafidi, Y. G. Sharabian, C. Carlin, R. G. Fersch, I. I. Strakovsky, S. S. Stepanyan, I. J. D. MacGregor, Andrew Puckett, T. A. Forest, V. Sytnik, P. L. Cole, B. Garillon, K. Livingston, Jie Zhang, Martin K. Mayer, R. W. Gothe, A. Deur, N. Kalantarians, Gerard Gilfoyle, J. Pierce, Avraham Klein, B. Vernarsky, Y. Ilieva, N. K. Walford, S. Chandavar, W. Kim, N. Guler, G. Niculescu, D. Sokhan, L. Colaneri, M. S. Saini, W. J. Briscoe, J. Bono, P. Nadel-Turonski, D. Doughty, Chaden Djalali, B. S. Ishkhanov, L. El Fassi, D. Keller, N. Markov, M. Taiuti, P. Rossi, S. Pisano, A. Simonyan, Sergey Kuleshov, R. Paremuzyan, G. E. Dodge, H. Y. Lu, M. Mirazita, P. Peng, H. Avakian, C. Munoz Camacho, A. El Alaoui, W. K. Brooks, F. X. Girod, Z. W. Zhao, D. P. Watts, I. Niculescu, B. McKinnon, N. Gevorgyan, D. Ho, J. P. Ball, M. Khandaker, Nicholas Zachariou, M. Ripani, L. L. Pappalardo, V. P. Kubarovsky, Andrea Celentano, S. E. Kuhn, A. Rizzo, D. Rimal, S. Procureur, J. A. Fleming, E. Munevar, Annalisa D'Angelo, S. Niccolai, D. G. Crabb, B. A. Raue, N. Dashyan, M. Battaglieri, H. Baghdasaryan, Lorenzo Zana, G. V. Fedotov, K. P. Adhikari, X. Jiang, E. Seder, M. Hattawy, C. Salgado, J. T. Goetz, O. Cortes, E. L. Isupov, R. Dupre, Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), CLAS, Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nuclear and High Energy Physics, Particle physics, FOS: Physical sciences, SPIN STRUCTURE, INELASTIC EP, SCATTERING, NUCLEON, CLAS, Electron, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, Settore FIS/04 - Fisica Nucleare e Subnucleare, NO, Nuclear physics, Invariant mass, Nuclear Experiment (nucl-ex), Nuclear Experiment, Quantum chromodynamics, Physics, Scattering, Polarization (waves), Deuterium, Quark–gluon plasma, High Energy Physics::Experiment, Nucleon
Abstract

The inclusive polarized structure functions of the proton and deuteron, g(1)(p) and g(1)(d) , were measured with high statistical precision using polarized 6 GeV electrons incident on a polarized ammonia target in Hall B at Jefferson Laboratory. Electrons scattered at laboratory angles between 18 and 45 degrees were detected using the CEBAF Large Acceptance Spectrometer (CLAS). For the usual deep inelastic region kinematics, Q(2) > 1 GeV2 and the final-state invariant mass W > 2 GeV, the ratio of polarized to unpolarized structure functions g(1)/F-1 is found to be nearly independent of Q(2) at fixed x. Significant resonant structure is apparent at values of W up to 2.3 GeV. In the framework of perturbative quantum chromodynamics, the high-W results can be used to better constrain the polarization of quarks and gluons in the nucleon, as well as high-twist contributions.

Published
2014

44. Exclusiveπ0electroproduction atW>2 GeV with CLAS

Author

Latifa Elouadrhiri, P. Lenisa, J. P. Ball, Y. Prok, H. Moutarde, D. S. Carman, G. V. Fedotov, E. De Sanctis, K. L. Giovanetti, Larry Weinstein, C. Djalali, A. Movsisyan, Friedrich Klein, D. I. Sober, H. Hakobyan, K. P. Adhikari, W. Phelps, Brian Raue, D. Doughty, W. Tang, P. Roy, E. Voutier, M. Osipenko, V. Crede, P. Eugenio, A. V. Vlassov, E. Golovatch, B. Guegan, S. Fegan, R. A. Montgomery, K. Livingston, Y. Ghandilyan, F. Sabatié, J. Bono, B. S. Ishkhanov, R. De Vita, I. Bedlinskiy, H. Y. Lu, A. D'Angelo, C. I. Moody, G. D. Smith, M. Holtrop, S. E. Kuhn, N. Dashyan, B. Garillon, M. Hattawy, J. A. Fleming, Z. W. Zhao, Barry Ritchie, Luciano Pappalardo, I. Zonta, S. Anefalos Pereira, S. Chandavar, H. Avakian, L. El Fassi, P. Stoler, W. J. Briscoe, W. Kim, X. Wei, S. Procureur, Lorenzo Zana, I. Niculescu, I. Senderovich, K. Hicks, M. Khandaker, N. K. Walford, H. Voskanyan, A. Kim, P. Rossi, L. Guo, W. I. Levine, R. A. Schumacher, S. Strauch, S. Park, Y. G. Sharabian, E. Seder, D. P. Watts, S. Niccolai, H. S. Jo, D. Protopopescu, H. Egiyan, A. Deur, P. L. Cole, N. Harrison, Andrew Puckett, T. A. Forest, M. Garçon, W. K. Brooks, R. Dupre, Alessandro Rizzo, Martin K. Mayer, Avraham Klein, P. Nadel-Turonski, M. Battaglieri, Sergey Kuleshov, A. El Alaoui, J. J. Phillips, Nicholas Zachariou, G. Gavalian, Dustin Keller, M. Ripani, K. Hafidi, A. Simonyan, C. Salgado, I. J. D. MacGregor, M. Yurov, S. S. Stepanyan, V. P. Kubarovsky, O. Pogorelko, V. Sytnik, M. Contalbrigo, Gerard Gilfoyle, L. Colaneri, N. Markov, D. Sokhan, A. Celentano, R. W. Gothe, S. Pisano, O. Cortes, E. L. Isupov, Ye Tian, Diane Schott, S. Boiarinov, A. I. Ostrovidov, K. Park, D. G. Ireland, Volker D. Burkert, A. S. Biselli, C. Munoz Camacho, B. McKinnon, M. Mirazita, E. Phelps, N. Gevorgyan, V. Batourine, F. X. Girod, J. W. Price, S. Koirala, D. G. Jenkins, Eugene Pasyuk, N. A. Baltzell, K. A. Griffioen, Victor Mokeev, M. Ungaro, K. Joo, and J. Zhang

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Meson, Structure function, Magnitude (mathematics), Parton, Helicity, Nuclear physics, Transverse plane, Pi, High Energy Physics::Experiment, Vector meson, Nuclear Experiment
Abstract

Exclusive neutral-pion electroproduction (ep-->e'p'pi0) was measured at Jefferson Lab with a 5.75-GeV electron beam and the CLAS detector. Differential cross sections d4sigma/dtdQ2dxBdphipi and structure functions sigmaT+epsilonsigmaL,sigmaTT and σLT as functions of t were obtained over a wide range of Q2 and xB. The data are compared with Regge and handbag theoretical calculations. Analyses in both frameworks find that a large dominance of transverse processes is necessary to explain the experimental results. For the Regge analysis it is found that the inclusion of vector meson rescattering processes is necessary to bring the magnitude of the calculated and measured structure functions into rough agreement. In the handbag framework, there are two independent calculations, both of which appear to roughly explain the magnitude of the structure functions in terms of transversity generalized parton distributions.

Published
2014

45. Induced polarization of {\Lambda}(1116) in kaon electroproduction

Author

B. S. Ishkhanov, A. Simonyan, W. Phelps, H. Hakobyan, H. S. Jo, C. A. Meyer, G. V. Fedotov, K. P. Adhikari, S. Strauch, P. Eugenio, S. E. Kuhn, M. Hattawy, J. A. Fleming, C. Salgado, F. X. Girod, V. P. Kubarovsky, Eugene Pasyuk, J. Bono, I. Bedlinskiy, P. Nadel-Turonski, N. Dashyan, S. Chandavar, O. Pogorelko, S. M. Hughes, F. Sabatié, M. J. Amaryan, S. Procureur, William Brooks, I. Zonta, X. Wei, H. Avakian, V. Baturin, Sergey Kuleshov, J. W. Price, N. K. Walford, B. Garillon, L. Zana, H. Voskanyan, H. Moutarde, R. Dupre, I. I. Strakovsky, M. Battaglieri, D. Ho, D. P. Watts, W. J. Briscoe, A. Deur, Yordanka Ilieva, S. Koirala, S. Niccolai, K. L. Giovanetti, S. S. Stepanyan, V. Sytnik, C. Djalali, Larry Weinstein, K. A. Griffioen, Alessandro Rizzo, Y. Ghandilyan, C. I. Moody, G. Charles, E. Golovatch, Dustin Keller, W. I. Levine, D. Adikaram, M. Guidal, G. Niculescu, D. G. Jenkins, R. A. Schumacher, G. D. Smith, M. Holtrop, M. Y. Gabrielyan, K. Hafidi, Luciano Pappalardo, M. Khandaker, J. P. Ball, T. A. Forest, D. S. Carman, M. Ripani, S. Stepanyan, E. Voutier, A. Movsisyan, E. Munevar, S. Fegan, V. Crede, A. V. Vlassov, R. De Vita, S. Anefalos Pereira, W. Tang, E. De Sanctis, M. Osipenko, D. I. Sober, W. Kim, Victor Mokeev, M. Ungaro, K. Joo, L. Guo, M. D. Mestayer, O. Cortes, Martin K. Mayer, S. Boiarinov, J. T. Goetz, K. Hicks, P. Lenisa, D. Doughty, Friedrich Klein, Brian Raue, A. D'Angelo, K. Livingston, L. El Fassi, R. Paremuzyan, Gerard Gilfoyle, J. J. Phillips, Jie Zhang, T. Cao, I. J. D. MacGregor, D. Sokhan, M. Contalbrigo, B. McKinnon, A. Celentano, R. W. Gothe, P. L. Cole, M. Mirazita, N. Gevorgyan, D. Protopopescu, S. Pozdniakov, P. Peng, C. Munoz Camacho, Diane Schott, N. A. Baltzell, K. Park, D. G. Ireland, H. Jiang, Volker D. Burkert, A. S. Biselli, Nicholas Zachariou, L. Colaneri, D. Rimal, S. Pisano, Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), CLAS, Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)

Subjects
Quark, Nuclear and High Energy Physics, Particle physics, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Induced polarization, DECAYS, Settore FIS/04 - Fisica Nucleare e Subnucleare, NO, Nuclear physics, CLAS, 0103 physical sciences, GAMMA-P, SIGMA(0), 010306 general physics, NUCLEON, Nuclear Experiment, PHOTON ENERGIES, PHOTOPRODUCTION, K+LAMBDA, SYSTEM, Physics, Spectrometer, 010308 nuclear & particles physics, Momentum transfer, Hyperon, Interaction model, Cathode ray, High Energy Physics::Experiment, Nucleon
Abstract

We have measured the induced polarization of the ${\Lambda}(1116)$ in the reaction $ep\rightarrow e'K^+{\Lambda}$, detecting the scattered $e'$ and $K^+$ in the final state along with the proton from the decay $\Lambda\rightarrow p\pi^-$.The present study used the CEBAF Large Acceptance Spectrometer (CLAS), which allowed for a large kinematic acceptance in invariant energy $W$ ($1.6\leq W \leq 2.7$ GeV) and covered the full range of the kaon production angle at an average momentum transfer $Q^2=1.90$ GeV$^2$.In this experiment a 5.50 GeV electron beam was incident upon an unpolarized liquid-hydrogen target. We have mapped out the $W$ and kaon production angle dependencies of the induced polarization and found striking differences from photoproduction data over most of the kinematic range studied. However, we also found that the induced polarization is essentially $Q^2$ independent in our kinematic domain, suggesting that somewhere below the $Q^2$ covered here there must be a strong $Q^2$ dependence. Along with previously published photo- and electroproduction cross sections and polarization observables, these data are needed for the development of models, such as effective field theories, and as input to coupled-channel analyses that can provide evidence of previously unobserved $s$-channel resonances., Comment: 13 figures

Published
2014

46. Data analysis techniques, differential cross sections, and spin density matrix elements for the reaction γp→ϕp

Author

D. P. Watts, A. V. Vlassov, E. Munevar, A. El Alaoui, Y. Ilieva, D. I. Glazier, R. Paremuzyan, B. S. Ishkhanov, A. Celentano, Nicholas Zachariou, R. W. Gothe, R. De Vita, Gerard Gilfoyle, D. Sokhan, K. Hafidi, H. Y. Lu, D. Rimal, A. Kim, W. Kim, S. Anefalos Pereira, H. S. Jo, B. McKinnon, G. Niculescu, C. Munoz Camacho, M. Mirazita, C. E. Hyde, M. Contalbrigo, N. Gevorgyan, S. Chandavar, A. Simonyan, F. Sabatié, N. A. Baltzell, E. De Sanctis, D. Protopopescu, M. Ungaro, J. P. Ball, D. S. Carman, D. Schott, R. A. Schumacher, M. Aghasyan, D. Keller, S. Pozdniakov, M. Garçon, J. W. Price, O. Cortes, J. J. Phillips, Michael L. Williams, D. I. Sober, B. Vernarsky, L. Colaneri, I. J. D. MacGregor, A. D'Angelo, I. Bedlinskiy, L. Zana, I. Zonta, R. Dupre, S. Boiarinov, P. Lenisa, V. P. Kubarovsky, K. A. Griffioen, N. Markov, M. Khandaker, I. I. Strakovsky, S. Pisano, V. Mokeev, K. Livingston, K. Joo, A. Deur, O. Pogorelko, Y. Ghandilyan, V. Sytnik, Avraham Klein, K. Park, N. Dashyan, M. J. Amaryan, L. El Fassi, D. G. Ireland, V. Crede, W. K. Brooks, Volker D. Burkert, A. S. Biselli, J. T. Goetz, T. Mineeva, C. Hanretty, H. Moutarde, D. Ho, Friedrich Klein, M. Bellis, I. Niculescu, R. A. Montgomery, K. L. Giovanetti, W. Tang, N. K. Walford, S. Niccolai, H. Voskanyan, M. Ripani, E. Voutier, M. Osipenko, M. Taiuti, D. Doughty, J. Zhang, Alessandro Rizzo, W. J. Briscoe, E. Pasyuk, P. Peng, Michael Dugger, P. Rossi, S. Procureur, M. Battaglieri, P. L. Cole, S. Fegan, M. E. McCracken, E. Seder, S. Strauch, Latifa Elouadrhiri, Kei Moriya, C. A. Meyer, G. V. Fedotov, K. P. Adhikari, Andrew Puckett, Martin K. Mayer, Barry Ritchie, M. S. Saini, S. E. Kuhn, M. Hattawy, S. Tkachenko, J. A. Fleming, Elton Smith, P. Roy, Y. G. Sharabian, N. Harrison, D. Adikaram, M. Guidal, C. Djalali, P. Stoler, M. Holtrop, B. Dey, I. Senderovich, K. Hicks, Luciano Pappalardo, Sergey Kuleshov, S. S. Stepanyan, J. Bono, P. Nadel-Turonski, F. X. Girod, S. Koirala, Z. W. Zhao, and D. G. Jenkins

Subjects
Physics, Nuclear and High Energy Physics, Scattering, Detector, Bremsstrahlung, Vector meson dominance, Settore FIS/04 - Fisica Nucleare e Subnucleare, Nuclear physics, Momentum, Matrix (mathematics), Vector meson, Atomic physics, Nuclear Experiment, Event (particle physics)
Abstract

High-statistics measurements of differential cross sections and spin density matrix elements for the reaction γ p → ϕ p have been made using the CLAS detector at Jefferson Lab. We cover center-of-mass energies ( s ) from 1.97 to 2.84 GeV, with an extensive coverage in the ϕ production angle. The high statistics of the data sample made it necessary to carefully account for the interplay between the ϕ natural lineshape and effects of the detector resolution, that are found to be comparable in magnitude. We study both the charged- ( ϕ → K + K − ) and neutral- ( ϕ → K S 0 K L 0 ) K K ¯ decay modes of the ϕ . Further, for the charged mode, we differentiate between the cases where the final K − track is directly detected or its momentum reconstructed as the total missing momentum in the event. The two charged-mode topologies and the neutral-mode have different resolutions and are calibrated against each other. Extensive usage is made of kinematic fitting to improve the reconstructed ϕ mass resolution. Our final results are reported in 10- and mostly 30-MeV-wide s bins for the charged- and the neutral-modes, respectively. Possible effects from K + Λ * channels with p K K ¯ final states are discussed. These present results constitute the most precise and extensive ϕ photoproduction measurements to date and in conjunction with the ω photoproduction results recently published by CLAS, will greatly improve our understanding of low energy vector meson photoproduction.

Published
2014

47. Measurement of the structure function of the nearly free neutron using spectator tagging in inelasticH2(e,e′ps)Xscattering with CLAS

Author

W. Kim, G. Niculescu, P. Lenisa, P. Nadel-Turonski, F. X. Girod, I. Zonta, X. Wei, B. McKinnon, A. Kim, S. Koirala, N. Dashyan, S. E. Kuhn, J. A. Fleming, M. Hattawy, B. S. Ishkhanov, Friedrich Klein, M. Mirazita, R. A. Schumacher, M. J. Amaryan, D. Dutta, N. A. Baltzell, J. Arrington, C. Djalali, S. Chandavar, Andrew Puckett, Martin K. Mayer, N. Gevorgyan, J. Zhang, L. Zana, V. Mokeev, K. A. Griffioen, H. Hakobyan, C. Hanretty, A. V. Vlassov, M. MacCormick, P. Eugenio, R. Paremuzyan, S. Bültmann, A. Simonyan, Latifa Elouadrhiri, G. Charles, S. Tkachenko, C. E. Hyde, K. L. Giovanetti, M. Ungaro, Larry Weinstein, M. Ripani, W. K. Brooks, R. Ent, I. Bedlinskiy, Gerard Gilfoyle, B. Garillon, D. Sokhan, Sergey Kuleshov, S. Stepanyan, Avraham Klein, G. V. Fedotov, V. P. Kubarovsky, K. P. Adhikari, D. Ho, Diane Schott, W. Tang, P. Roy, M. Osipenko, O. Pogorelko, Andrea Celentano, R. De Vita, S. Strauch, D. P. Watts, P. L. Cole, C. E. Keppel, D. Doughty, M. Guidal, D. G. Ireland, George Davey Smith, K. Park, V. Crede, M. Ispiryan, I. J. D. MacGregor, S. Lewis, H. Avakian, G. Rosner, R. A. Montgomery, R. Dupre, M. Battaglieri, C. Munoz Camacho, J. P. Ball, M. Holtrop, N. K. Walford, D. S. Carman, H. Voskanyan, M. Khandaker, Y. Ghandilyan, Volker D. Burkert, A. S. Biselli, S. Anefalos Pereira, Eugene Pasyuk, E. Seder, H. S. Jo, W. J. Briscoe, S. Niccolai, A. D'Angelo, Luciano Pappalardo, G. E. Dodge, H. Y. Lu, N. Markov, Dustin Keller, E. De Sanctis, S. S. Stepanyan, S. Pisano, M. Aghasyan, Michael Wood, K. Hafidi, D. I. Sober, I. Niculescu, L. El Fassi, K. Hicks, H. Egiyan, T. Mineeva, P. Bosted, M. E. Christy, L. Guo, I. Senderovich, Alessandro Rizzo, J. T. Goetz, O. Cortes, N. Harrison, H. Fenker, P. M. King, E. Golovatch, N. Baillie, A. Deur, N. Kalantarians, J. W. Price, D. Protopopescu, S. Pozdniakov, E. Voutier, K. Livingston, Y. G. Sharabian, F. Sabatié, P. Rossi, A. El Alaoui, Y. Ilieva, D. Rimal, M. Contalbrigo, W. Melnitchouk, V. Tvaskis, S. Procureur, R. W. Gothe, H. Moutarde, and J. J. Phillips

Subjects
Nuclear physics, Physics, Nuclear and High Energy Physics, Proton, Dynamic structure factor, Nuclear Theory, EMC effect, Momentum transfer, Neutron, Nuclear Experiment, Nucleon, Inelastic neutron scattering, Neutron time-of-flight scattering
Abstract

Background: Much less is known about neutron structure than that of the proton due to the absence of free neutron targets. Neutron information is usually extracted from data on nuclear targets such as deuterium, requiring corrections for nuclear binding and nucleon off-shell effects. These corrections are model dependent and have significant uncertainties, especially for large values of the Bjorken scaling variable x . As a consequence, the same data can lead to different conclusions, for example, about the behavior of the d quark distribution in the proton at large x . Purpose: The Barely Off-shell Nucleon Structure experiment at Jefferson Lab measured the inelastic electron-deuteron scattering cross section, tagging spectator protons in coincidence with the scattered electrons. This method reduces nuclear binding uncertainties significantly and has allowed for the first time a (nearly) model-independent extraction of the neutron structure function F 2 ( x , Q 2 ) in the resonance and deep-inelastic regions. Method: A novel compact radial time projection chamber was built to detect protons with momentum between 70 and 150 MeV / c and over a nearly 4 π angular range. For the extraction of the free-neutron structure function F 2 n , spectator protons at backward angles ( > 100 ∘ relative to the momentum transfer) and with momenta below 100 MeV / c were selected, ensuring that the scattering took place on a nearly free neutron. The scattered electrons were detected with Jefferson Lab's CLAS spectrometer, with data taken at beam energies near 2, 4, and 5 GeV. Results: The extracted neutron structure function F 2 n and its ratio to the inclusive deuteron structure function F 2 d are presented in both the resonance and the deep-inelastic regions for momentum transfer squared Q 2 between 0.7 and 5 GeV 2 / c 2 , invariant mass W between 1 and 2.7 GeV / c 2 , and Bjorken x between 0.25 and 0.6 (in the deep-inelastic scattering region). The dependence of the semi-inclusive cross section on the spectator proton momentum and angle is investigated, and tests of the spectator mechanism for different kinematics are performed. Conclusions: Our data set on the structure function ratio F 2 n / F 2 d can be used to study neutron resonance excitations, test quark-hadron duality in the neutron, develop more precise parametrizations of structure functions, and investigate binding effects (including possible mechanisms for the nuclear EMC effect) and provide a first glimpse of the asymptotic behavior of d / u at x → 1 .

Published
2014

48. Publisher's Note: Beam asymmetryΣforπ+andπ0photoproduction on the proton for photon energies from 1.102 to 1.862 GeV [Phys. Rev. C88, 065203 (2013)]

Author

L. Elouadrhiri, N. A. Baltzell, I. I. Strakovsky, C. S. Nepali, George Davey Smith, A. Deur, M. Contalbrigo, R. Paremuzyan, S. Fegan, D. Adikaram, M. Guidal, F. X. Girod, E. De Sanctis, A. D'Angelo, V. Mokeev, G. Niculescu, M. Khandaker, W. Tang, M. Aghasyan, M. Osipenko, Nicholas M. Harrison, Gerard Gilfoyle, M. Holtrop, D. I. Sober, A. El Alaoui, Nicholas Zachariou, L. El Fassi, D. Martinez, I. J. D. MacGregor, S. Park, D. Sokhan, S. Strauch, N. Dashyan, Luciano Pappalardo, P. Nadel-Turonski, P. Rossi, D. Rimal, I. Zonta, C. Djalali, A. Celentano, R. W. Gothe, D. P. Watts, W. Gohn, H. Y. Lu, S. Koirala, H. Egiyan, M. J. Amaryan, K. Livingston, Frank Klein, D. G. Ireland, Dustin Keller, Yordanka Ilieva, Diane Schott, E. Munevar, A. I. Ostrovidov, K. Park, R. De Vita, B. S. Ishkhanov, Michael Dugger, Sergey Kuleshov, Yakov I. Azimov, Brian Raue, H. Moutarde, V. Crede, E. Golovatch, A. Kubarovsky, K. A. Griffioen, N. K. Walford, I. Niculescu, N. Guler, K. L. Giovanetti, J. J. Phillips, K. Hafidi, S. Anefalos Pereira, R. A. Montgomery, P. Stoler, Ron L. Workman, V. Batourine, D. Doughty, G. Rosner, P. L. Cole, Z. W. Zhao, Volker D. Burkert, A. S. Biselli, R. A. Schumacher, S. Niccolai, D. Heddle, J. P. Ball, Y. Prok, D. S. Carman, F. Sabatié, K. Hicks, C. Hanretty, J. Zhang, S. Chandavar, S. Tkachenko, T. Mineeva, D. Protopopescu, J. W. Price, H. Avakian, P. Peng, B. Torayev, S. Pozdniakov, I. Senderovich, Alessandro Rizzo, E. Voutier, L. Guo, M. Ungaro, C. Munoz Camacho, S. Stepanyan, I. Bedlinskiy, Andreas Klein, M. Ripani, A. Kim, B. McKinnon, H. Voskanyan, K. Joo, Carlos A. Salgado, M. Mirazita, E. Phelps, W. J. Briscoe, E. Pasyuk, N. Gevorgyan, S. Procureur, S. Pisano, R. Dupre, M. Battaglieri, J. A. Fleming, V. P. Kubarovsky, P. Collins, O. Pogorelko, S. Lewis, Martin K. Mayer, M. S. Saini, J. T. Goetz, H. Seraydaryan, Y. G. Sharabian, P. Eugenio, M. Taiuti, D. Ho, E. Seder, Barry Ritchie, O. Cortes, E. L. Isupov, Ye Tian, S. Boiarinov, G. V. Fedotov, D. P. Weygand, K. P. Adhikari, Lorenzo Zana, H. Hakobyan, H. S. Jo, and W. Kim

Subjects
Nuclear physics, Physics, Nuclear and High Energy Physics, Particle physics, Meson production, Photon, Proton, Partial wave analysis, media_common.quotation_subject, Asymmetry, Beam (structure), media_common
Published
2014

49. Momentum sharing in imbalanced Fermi systems

Author

W. Kim, G. Niculescu, S. Chandavar, J. T. Goetz, A. Kim, P. Lenisa, C. E. Hyde, I. Niculescu, N. A. Baltzell, H. Hakobyan, Friedrich Klein, J. Ball, D. Doughty, C. Hanretty, D. Rimal, Shalev Gilad, F. Sabatié, A. El Alaoui, R. Dupre, M. Battaglieri, S. Fegan, Chaden Djalali, S. May-Tal Beck, P. Stoler, Nicholas Zachariou, Michael Dugger, M. Ripani, John Arrington, T. Cao, William Brooks, A. Deur, J. W. Price, M. Lowry, I. J. D. MacGregor, G. Rosner, H. Y. Lu, O. Pogorelko, Diane Schott, R. Shneor, I. Bedlinskiy, K. Park, S. Koirala, Y. Ilieva, Latifa Elouadrhiri, E. L. Isupov, M. Ungaro, D. G. Ireland, R. A. Schumacher, D. Protopopescu, N. Markov, H. Jiang, Volker D. Burkert, Y. Ghandilyan, A. S. Biselli, R. De Vita, L. L. Pappalardo, I. Zonta, G. V. Fedotov, X. Wei, S. Strauch, Douglas Higinbotham, L. Colaneri, M. Osipenko, A. Beck, K. Livingston, L. El Fassi, Lorenzo Zana, T. A. Forest, S. Stepanyan, Misak Sargsian, Hovanes Egiyan, C. Munoz Camacho, S. Pisano, K. P. Adhikari, M. Taiuti, M. Braverman, R. Paremuzyan, K. A. Griffioen, M. Mayer, Larry Weinstein, William Bertozzi, D. Keller, T. Mineeva, D. S. Carman, Andrea Celentano, Barry Ritchie, Gerard Gilfoyle, K. Joo, Eli Piasetzky, S. E. Kuhn, D. Sokhan, M. Hattawy, P. L. Cole, M. Khandaker, P. Rossi, R. W. Gothe, F. X. Girod, B. Garillon, V. Crede, B. McKinnon, S. A. Wood, Z. W. Zhao, N. Gevorgyan, P. Nadel-Turonski, M. Garçon, W. I. Levine, Victor Mokeev, E. Voutier, Y. G. Sharabian, X. Zheng, Andrew Puckett, H. S. Jo, A. V. Vlassov, S. Tkachenko, L. Guo, G. Asryan, K. Hicks, Y. Prok, W. Phelps, A. Rizzo, S. Niccolai, A. Movsisyan, S. S. Stepanyan, E. Pasyuk, V. Sytnik, Or Hen, I. Korover, P. Roy, M. Guidal, B. Mustapha, B. I. Ishkanov, G. D. Smith, M. Holtrop, S. Procureur, V. P. Kubarovsky, Annalisa D'Angelo, Michael Wood, K. Hafidi, H. Avakian, N. K. Walford, Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), CLAS Collaboration, Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS), and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nuclear Theory, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, Settore FIS/04 - Fisica Nucleare e Subnucleare, Nuclear physics, Nuclear Theory (nucl-th), symbols.namesake, Pauli exclusion principle, Semi-empirical mass formula, Nuclear force, Nuclear drip line, Nuclear Experiment (nucl-ex), Nuclear Experiment, Condensed Matter::Quantum Gases, Physics, Multidisciplinary, Fermi energy, Quantum Gases (cond-mat.quant-gas), Atomic nucleus, Nuclear magnetic moment, symbols, Condensed Matter - Quantum Gases, Fermi gas
Abstract

The atomic nucleus is composed of two different kinds of fermions, protons and neutrons. If the protons and neutrons did not interact, the Pauli exclusion principle would force the majority fermions (usually neutrons) to have a higher average momentum. Our high-energy electron scattering measurements using 12C, 27Al, 56Fe and 208Pb targets show that, even in heavy neutron-rich nuclei, short-range interactions between the fermions form correlated high-momentum neutron-proton pairs. Thus, in neutron-rich nuclei, protons have a greater probability than neutrons to have momentum greater than the Fermi momentum. This finding has implications ranging from nuclear few body systems to neutron stars and may also be observable experimentally in two-spin state, ultra-cold atomic gas systems., Comment: Published in Science. 10 pages, 3 figures

Published
2014

50. Exclusive π0 electroproduction at W>2 GeV with CLAS

Author

I. BedlinskiyInstitute of Theoretical and Experimental Physics, V. Kubarovsky(Thomas Jefferson National Accelerator Facility), S. Niccolai(Institut de Physique Nucléaire ORSAY), P. Stoler(Rensselaer Polytechnic Institute), K. P. Adhikari(Old Dominion University), M. D. Anderson(University of Glasgow), S. Anefalos Pereira(INFN), H. Avakian(Thomas Jefferson National Accelerator Facility), J. Ball(CEA), N. A. Baltzell(Argonne National Laboratory), M. Battaglieri(INFN), V. Batourine(Thomas Jefferson National Accelerator Facility), A. S. Biselli(Thomas Jefferson National Accelerator Facility), S. Boiarinov(Thomas Jefferson National Accelerator Facility), J. Bono(Florida International University), W. J. Briscoe(The George Washington University), W. K. Brooks(Universidad Técnica Federico Santa María), V. D. Burkert(Thomas Jefferson National Accelerator Facility), D. S. Carman(Thomas Jefferson National Accelerator Facility), A. Celentano(INFN), S. Chandavar(Ohio University), L. Colaneri(INFN), P. L. Cole(Idaho State University), M. Contalbrigo(INFN), O. Cortes(Idaho State University), V. Crede(Florida State University), A. D'Angelo(INFN), N. Dashyan(Yerevan Physics Institute), R. De Vita(INFN), E. De Sanctis(INFN), A. Deur(Thomas Jefferson National Accelerator Facility), C. Djalali(University of South Carolina), D. Doughty(Christopher Newport University), R. Dupre(Institut de Physique Nucléaire ORSAY), H. Egiyan(Thomas Jefferson National Accelerator Facility), A. El Alaoui(Argonne National Laboratory), L. El Fassi(Old Dominion University), L. Elouadrhiri(Thomas Jefferson National Accelerator Facility), P. Eugenio(Florida State University), G. Fedotov(University of South Carolina), S. Fegan(INFN), J. A. Fleming(Edinburgh University), T. A. Forest(Idaho State University), B. Garillon(Institut de Physique Nucléaire ORSAY), M. Gar\c con(CEA), G. Gavalian(Old Dominion University), N. Gevorgyan(Yerevan Physics Institute), Y. Ghandilyan(Yerevan Physics Institute), G. P. Gilfoyle(University of Richmond), K. L. Giovanetti(James Madison University), F. X. Girod(Thomas Jefferson National Accelerator Facility), E. Golovatch(Skobeltsyn Institute of Nuclear Physics), R. W. Gothe(University of South Carolina), K. A. Griffioen(Institut de Physique Nucléaire ORSAY), B. Guegan(Institut de Physique Nucléaire ORSAY), L. Guo(Florida International University), K. Hafidi(Argonne National Laboratory), H. Hakobyan(Universidad Técnica Federico Santa María), N. Harrison(University of Connecticut), M. Hattawy(Institut de Physique Nucléaire ORSAY), K. Hicks(Ohio University), M. Holtrop(University of New Hampshire), D. G. Ireland(University of Glasgow), B. S. Ishkhanov(Skobeltsyn Institute of Nuclear Physics), E. L. Isupov(Skobeltsyn Institute of Nuclear Physics), D. Jenkins(Institut de Physique Nucléaire ORSAY), H. S. Jo(Institut de Physique Nucléaire ORSAY), K. Joo(University of Connecticut), D. Keller(University of Virginia), M. Khandaker(Idaho State University), A. Kim(University of Connecticut), W. Kim(Kyungpook National University), A. Klein(Old Dominion University), F. J. Klein(Catholic University of America), S. Koirala(Old Dominion University), S. E. Kuhn(Old Dominion University), S. V. Kuleshov(Universidad Técnica Federico Santa María), P. Lenisa(INFN), W. I. Levine(Carnegie Mellon University), K. Livingston(University of Glasgow), H. Y. Lu(University of South Carolina), I . J . D. MacGregor(University of Glasgow), N. Markov(University of Connecticut), M. Mayer(Old Dominion University), B. McKinnon(University of Glasgow), M. Mirazita(INFN), V. Mokeev(Thomas Jefferson National Accelerator Facility), R. A. Montgomery(INFN), C. I. Moody(Argonne National Laboratory), H. Moutarde(CEA), A Movsisyan(INFN), C. Munoz Camacho(Institut de Physique Nucléaire ORSAY), P. Nadel-Turonski(Thomas Jefferson National Accelerator Facility), I. Niculescu(James Madison University), M. Osipenko(INFN), A. I. Ostrovidov(Florida State University), L. L. Pappalardo(INFN), K. Park(Thomas Jefferson National Accelerator Facility), S. Park(Florida State University), E. Pasyuk(Thomas Jefferson National Accelerator Facility), E. Phelps(University of South Carolina), W. Phelps(Florida International University), J. J. Phillips(University of Glasgow), S. Pisano(INFN), O. Pogorelko(Institute of Theoretical and Experimental Physics), J. W. Price(California State University), Y. Prok(Old Dominion University), D. Protopopescu(University of Glasgow), S. Procureur(CEA), A. J. R. Puckett(University of Connecticut), B. A. Raue(Florida International University), M. Ripani(INFN), B. G. Ritchie(Arizona State University), A. Rizzo(INFN), P. Rossi(INFN), P. Roy(Florida State University), F. Sabatié(CEA), C. Salgado(Norfolk State University), D. Schott(The George Washington University), R. A. Schumacher(Carnegie Mellon University), E. Seder(University of Connecticut), I. Senderovich(Arizona State University), Y. G. Sharabian(Thomas Jefferson National Accelerator Facility), A. Simonyan(Yerevan Physics Institute), G. D. Smith(Edinburgh University), D. I. Sober(Catholic University of America), D. Sokhan(University of Glasgow), S. S. Stepanyan(Kyungpook National University), S. Strauch(University of South Carolina), V. Sytnik(Universidad Técnica Federico Santa María), W. Tang(Ohio University), Ye Tian(University of South Carolina), M. Ungaro(Thomas Jefferson National Accelerator Facility), A. V. Vlassov(Institute of Theoretical and Experimental Physics), H. Voskanyan(Yerevan Physics Institute), E. Voutier(LPSC), N. K. Walford(Catholic University of America), D. Watts(University of Glasgow), X. Wei(Thomas Jefferson National Accelerator Facility), L. B. Weinstein(Old Dominion University), M. Yurov(University of Virginia), N. Zachariou(University of South Carolina), L. Zana(Edinburgh University), J. Zhang(Thomas Jefferson National Accelerator Facility), Z. W. Zhao(University of Virginia), I. Zonta(INFN), and for the CLAS Collaboration()

Subjects
hep-ex, High Energy Physics::Experiment, Nuclear Experiment, nucl-ex, NO
Abstract

Exclusive neutral-pion electroproduction ($ep\to e^\prime p^\prime \pi^0$) was measured at Jefferson Lab with a 5.75-GeV electron beam and the CLAS detector. Differential cross sections $d^4\sigma/dtdQ^2dx_Bd\phi_\pi$ and structure functions $\sigma_T+\epsilon\sigma_L, \sigma_{TT}$ and $\sigma_{LT}$ as functions of $t$ were obtained over a wide range of $Q^2$ and $x_B$. The data are compared with Regge and handbag theoretical calculations. Analyses in both frameworks find that a large dominance of transverse processes is necessary to explain the experimental results. For the Regge analysis it is found that the inclusion of vector meson rescattering processes is necessary to bring the magnitude of the calculated and measured structure functions into rough agreement. In the handbag framework, there are two independent calculations, both of which appear to roughly explain the magnitude of the structure functions in terms of transversity generalized parton distributions.

Published
2014

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