Author: "Nicholas Zachariou" / Publisher: american physical society (aps) - Searchworks@Jio Institute Digital Library Search Results

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1. Improved Λp Elastic Scattering Cross Sections between 0.9 and 2.0 GeV/c as a Main Ingredient of the Neutron Star Equation of State

Author: Zein-Eddine Meziani, Mathieu Ehrhart, Nicholas Zachariou, Annalisa D'Angelo, Marco Contalbrigo, David Ireland, Marco Battaglieri, Mikhail Bashkanov, Lucilla Lanza, Michael Wood, Luca Marsicano, Axel Schmidt, and Giovanni Costantini
Subjects: 010308 nuclear & particles physics, 0103 physical sciences, General Physics and Astronomy, 010306 general physics, 01 natural sciences
Published: 2021

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. 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

4. 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

5. 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

6. Photoproduction of η mesons off the proton for 1.2<Eγ<4.7GeV using CLAS at Jefferson Laboratory

Author: I. Illari, R. A. Schumacher, U. Shrestha, M. Leali, S. Adhikari, B. McKinnon, C. A. Meyer, E. Munevar, P. Chatagnon, B. S. Ishkhanov, Aditya R. Khanal, G. V. Fedotov, P. Lenisa, J. Ritman, S. Stepanyan, N. Dashyan, D. P. Watts, Andrea Bianconi, M. Ungaro, K. P. Adhikari, A. El Alaoui, I. I. Strakovsky, G. Rosner, T. Chetry, A. Deur, C. W. Kim, Laura Clark, W. Phelps, M. Battaglieri, Nicholas Zachariou, J. C. Carvajal, Alexander Schmidt, M. J. Amaryan, William Brooks, Yordanka Ilieva, T. B. Hayward, V. Mascagna, B. A. Clary, E. L. Isupov, Y. G. Sharabian, H. Voskanyan, Friedrich Klein, W. J. Briscoe, P. Eugenio, S. Boiarinov, Brian Raue, G. Angelini, L. Barion, K. Joo, M. Guidal, Michael Paolone, Z. W. Zhao, F. X. Girod, F. Bossu, R. Cruz-Torres, E. Golovatch, M. Holtrop, R. Dupre, S. Strauch, Hovanes Egiyan, Maxime Defurne, K. A. Griffioen, Dustin Keller, C. Munoz Camacho, H. Hakobyan, Y. Prok, H. S. Jo, M. Hattawy, Michael Wood, K. Hafidi, D. G. Ireland, Luciano Pappalardo, V. Crede, A. Kim, D. I. Glazier, G. Ciullo, D. S. Carman, F. Sabatié, T. Hu, R. Paremuzyan, R. De Vita, D. Marchand, D. Protopopescu, Eugene Pasyuk, X. Wei, L. Venturelli, S. Diehl, Fatiha Benmokhtar, O. Soto, C. Salgado, E. Voutier, L. Lanza, Nicholas M. Harrison, Gerard Gilfoyle, A. Filippi, A. Movsisyan, J. W. Price, D. Sokhan, V. P. Kubarovsky, I. Bedlinskiy, M. Khandaker, M. Khachatryan, Nikolaos Sparveris, Z. E. Meziani, K. Wei, S. Niccolai, K. Livingston, N. Markov, Iu. Skorodumina, N. Tyler, C. Djalali, J. A. Tan, V. I. Mokeev, D. Heddle, Jie Zhang, G. Gavalian, D. G. Jenkins, R. Fersch, M. Ehrhart, M. Ripani, O. Pogorelko, P. L. Cole, J. Rowley, Tim O'Connell, A. I. Ostrovidov, Michael Dugger, T. Mineeva, P. Nadel-Turonski, H. Atac, A. S. Biselli, A. D'Angelo, L. Guo, Sylvester Joosten, Alessandro Rizzo, G. Asryan, L. El Fassi, C. Ayerbe Gayoso, M. E. McCracken, A. Hobart, C. Hanretty, W. Kim, G. Niculescu, P. Stoler, M. Osipenko, I. J. D. MacGregor, K. Hicks, M. Contalbrigo, J. Poudel, Z. Akbar, A. Celentano, and R. W. Gothe
Subjects: Physics, Particle physics, Range (particle radiation), Photon, Proton, Meson, 010308 nuclear & particles physics, Sigma, Photon energy, 01 natural sciences, 7. Clean energy, Resonance (particle physics), 0103 physical sciences, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, Nucleon
Abstract: Photoproduction cross sections are reported for the reaction $\gamma p\to p\eta$ using energy-tagged photons and the CLAS spectrometer at Jefferson Laboratory. The $\eta$ mesons are detected in their dominant charged decay mode, $\eta\to \pi^+\pi^-\pi^0$, and results on differential cross sections are presented for incident photon energies between 1.2 and 4.7 GeV. These new $\eta$ photoproduction data are consistent with earlier CLAS results but extend the energy range beyond the nucleon resonance region into the Regge regime. The normalized angular distributions are compared with the experimental results from several other experiments, and with predictions of $\eta$ MAID\,2018 and the latest solution of the Bonn-Gatchina coupled-channel analysis. Differential cross sections $d\sigma/dt$ are presented for incident photon energies $E_\gamma > 2.9$ GeV ($W > 2.5$ GeV), and compared with predictions which are based on Regge trajectories exchange in the $t$-channel (Regge models). The data confirm the expected dominance of $\rho$, $\omega$ vector-meson exchange in an analysis by the Joint Physics Analysis Center.
Published: 2020

7. First measurement of direct photoproduction of the a2(1320)0 meson on the proton

Author: J. Rowley, A. I. Ostrovidov, Volker D. Burkert, A. S. Biselli, W. Phelps, K. A. Griffioen, V. Mascagna, N. Markov, M. E. McCracken, A. Hobart, Carlos A. Salgado, A. Filippi, A. Pilloni, Frank Klein, Dustin Keller, P. Eugenio, L. Marsicano, Sylvester Joosten, Maxime Defurne, M. Khandaker, M. Khachatryan, M. Osipenko, Pawel Nadel-Turonski, Michael Paolone, Alexander Schmidt, D. I. Glazier, D. Bulumulla, E. Munevar, B. S. Ishkhanov, Aditya R. Khanal, Nikolaos Sparveris, M. Ungaro, K. Hafidi, F. Bossu, M. Guidal, G. Niculescu, L. Lanza, D. G. Jenkins, I. J. D. MacGregor, R. De Vita, M. Leali, Laura Clark, M. J. Amaryan, Andrea Bianconi, C. W. Kim, W. Kim, W. Gohn, F. X. Girod, N. Tyler, C. Djalali, J. A. Tan, P. Chatagnon, G. V. Fedotov, H. Voskanyan, A. D'Angelo, T. Chetry, I. Bedlinskiy, L. Elouadrhiri, M. Holtrop, F. Hauenstein, W. J. Briscoe, E. Pasyuk, S. Strauch, K. Joo, H. Atac, D. P. Watts, H. Egiyan, G. Angelini, L. El Fassi, I. I. Strakovsky, R. Dupre, M. Battaglieri, F. Sabatié, Luciano Pappalardo, D. Heddle, A. Deur, M. Ripani, G. Gavalian, V. Mokeev, D. Marchand, V. Lucherini, V. P. Kubarovsky, Michael Dugger, Fatiha Benmokhtar, Krishna Neupane, R. G. Fersch, O. Pogorelko, O. Soto, S. Niccolai, Vincent Mathieu, P. L. Cole, Z. W. Zhao, Alessandro Rizzo, E. Golovatch, P. Lenisa, K. Hicks, M. Ehrhart, S. Adhikari, T. B. Hayward, J. Zhang, M. Hattawy, J. W. Price, N. Dashyan, Yordanka Ilieva, L. Barion, G. Rosner, William Brooks, G. Ciullo, Y. Prok, L. Venturelli, D. S. Carman, R. A. Schumacher, A. El Alaoui, X. Wei, Nicholas Zachariou, J. C. Carvajal, S. Stepanyan, E. Voutier, A. Movsisyan, Adam P. Szczepaniak, D. Sokan, Z. E. Meziani, K. Livingston, K. P. Adhikari, H. Hakobyan, H. S. Jo, A. Kim, J. Ritman, S. Diehl, D. G. Ireland, V. Crede, O. Cortes, E. L. Isupov, R. Paremuzyan, S. Boiarinov, R. Cruz-Torres, Nicholas M. Harrison, U. Shrestha, M. Contalbrigo, C. Munoz Camacho, M. H. Wood, B. McKinnon, A. Celentano, R. W. Gothe, M. Mirazita, and N. Gevorgyan
Subjects: Physics, Meson, 010308 nuclear & particles physics, Partial wave analysis, Hadron, Sigma, Photon energy, 01 natural sciences, Nuclear physics, Amplitude, 0103 physical sciences, Invariant mass, Nuclear Experiment, 010306 general physics, Phenomenology (particle physics)
Abstract: We present the first measurement of the exclusive reaction $\gamma p \rightarrow a_2(1320)^0 \, p$ in the photon energy range $3.5$-$5.5$ GeV and four-momentum transfer squared $0.2
Published: 2020

8. Signatures of the d*(2380) Hexaquark in d(γ,pn→)

Author: M. Bashkanov, R. A. Miskimen, M. Biroth, Yu. A. Usov, O. Steffen, P. Pedroni, P. B. Otte, Michaela Thiel, S. Abt, C. S. Akondi, A. B. Lazarev, A. Braghieri, Th. Strub, Concettina Sfienti, L.A. Zana, M. Korolija, K. Livingston, S. Lutterer, David Manley, V. L. Kashevarov, W. Gradl, S. Gardner, N. S. Borisov, D. Hornidge, P. P. Martel, Z. Ahmed, N. K. Walford, J. Wettig, S. Fegan, I. I. Strakovsky, F. Cividini, Susanna Costanza, H. J. Arends, D. Ghosal, Guy Ron, S. Wagner, K. Spieker, A. Käser, V. Sokhoyan, C. Mullen, R. Beck, P. Adlarson, A. Fix, A. G. Denig, M. Ostrick, Durga Paudyal, Nicholas Zachariou, D. P. Watts, Patrick Achenbach, A. Neiser, E. J. Downie, D. Gurevich, M. Wolfes, I. Supek, C. Collicott, I. Gorodnov, A. Thiel, F. Afzal, W. J. Briscoe, A. B. Neganov, D. Werthmüller, M. Günther, Lena Heijkenskjöld, I. J. D. MacGregor, P. Drexler, S. N. Prakhov, J. R. M. Annand, Andy Thomas, G. M. Huber, D. I. Glazier, S. Kay, A. Powell, A. Sarty, E. Mornacchi, and B. Krusche
Subjects: Physics, Photon, Spin polarization, Nuclear Theory, General Physics and Astronomy, Photon energy, 01 natural sciences, Nuclear physics, Recoil, Photodisintegration, 0103 physical sciences, Neutron, Nuclear Experiment, 010306 general physics, Nucleon, Crystal Ball
Abstract: We report a measurement of the spin polarization of the recoiling neutron in deuterium photodisintegration, utilizing a new large acceptance polarimeter within the Crystal Ball at MAMI. The measured photon energy range of 300-700 MeV provides the first measurement of recoil neutron polarization at photon energies where the quark substructure of the deuteron plays a role, thereby providing important new constraints on photodisintegration mechanisms. A very high neutron polarization in a narrow structure centered around E_{γ}∼570 MeV is observed, which is inconsistent with current theoretical predictions employing nucleon resonance degrees of freedom. A Legendre polynomial decomposition suggests this behavior could be related to the excitation of the d^{*}(2380) hexaquark.
Published: 2020

9. 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

10. Cross section for γn→π0n measured at the Mainz A2 experiment

Author: K. Livingston, S. Lutterer, S. Gardner, N. S. Borisov, M. Unverzagt, V. V. Kulikov, H. J. Arends, A. B. Lazarev, A. Neiser, Alfred Švarc, F. Cividini, A. Braghieri, F. Afzal, D. G. Middleton, B. Oussena, C. Collicott, D. P. Watts, K. Spieker, K. Bantawa, M. Bashkanov, R. A. Miskimen, M. Ostrick, S. Kay, C. Sfienti, V. E. Tarasov, Patrick Achenbach, Yu. A. Usov, G. M. Huber, A. E. Kudryavtsev, A. Käser, O. Steffen, P. Aguar-Bartolomé, V. L. Kashevarov, A. G. Denig, E. J. Downie, N. K. Walford, J. Wettig, E. Mornacchi, A. Thiel, J. Stahov, S. Fegan, Durga Paudyal, J. C. McGeorge, Nicholas Zachariou, V. Sokhoyan, I. J. D. MacGregor, M. I. Ferretti Bondy, M. A. Martemianov, D. Gurevich, D. Hornidge, D. Ghosal, S. Wagner, M. Wolfes, Anthony W. Thomas, D. I. Glazier, Guy Ron, Z. Ahmed, Susanna Costanza, Michaela Thiel, W. J. Briscoe, A. Powell, M. Günther, L. Tiator, I. I. Strakovsky, A. N. Mushkarenkov, S. A. Bulychjov, D. M. Manley, Lena Heijkenskjöld, P. P. Martel, R. Omerović, M. Korolija, R. Beck, C. Mullen, J. R. M. Annand, D. Werthmüller, M. Biroth, M. Hadžimehmedović, P. B. Otte, A. B. Neganov, P. Pedroni, W. Gradl, S. N. Prakhov, B. Krusche, P. Drexler, H. Osmanović, T. Rostomyan, I. Supek, I. Gorodnov, Ron L. Workman, Roderick M. Macrae, S. Abt, C. S. Akondi, and A. J. Sarty
Subjects: Physics, 010308 nuclear & particles physics, Nuclear Theory, 7. Clean energy, 01 natural sciences, Resonance (particle physics), Nuclear physics, Cross section (physics), Pion, Amplitude, Deuterium, Reaction dynamics, 0103 physical sciences, Neutron, Nuclear Experiment, 010306 general physics, Microtron
Abstract: The γ n → π 0 n differential cross section evaluated for 27 energy bins span the photon-energy range 290–813 MeV ( W = 1.195 –1.553 GeV) and the pion c.m. polar production angles, ranging from 18 ∘ to 162 ∘ , making use of model-dependent nuclear corrections to extract π 0 production data on the neutron from measurements on the deuteron target. Additionally, the total photoabsorption cross section was measured. The tagged photon beam produced by the 883 MeV electron beam of the Mainz Microtron MAMI was used for the π 0 -meson production. Our accumulation of 3.6 × 10 6 γ n → π 0 n events allowed a detailed study of the reaction dynamics. Our data are in reasonable agreement with previous A2 measurements and extend them to lower energies. The data are compared with predictions of previous said, maid, and BnGa partial-wave analyses and to the latest said fit MA19 that included our data. Selected photon-decay amplitudes N ∗ → γ n at the resonance poles are determined for the first time.
Published: 2019

11. First Measurements of the Double-Polarization Observables F , P , and H in ω Photoproduction off Transversely Polarized Protons in the N* Resonance Region

Author: Eberhard Klempt, O. Cortes, C. Hanretty, K. A. Griffioen, M. Ungaro, V. A. Nikonov, X. Wei, B. S. Ishkhanov, O. Soto, C. D. Keith, S. Strauch, G. Khachatryan, F. X. Girod, M. Osipenko, A. D'Angelo, Eugene Pasyuk, H. S. Jo, A. El Alaoui, W. J. Briscoe, Y. Ilieva, Aditya R. Khanal, Dustin Keller, L. Barion, F. Sabatié, I. I. Strakovsky, L. Guo, Alessandro Rizzo, A. V. Anisovich, L. Lanza, J. Brock, V. Mokeev, E. L. Isupov, Nicholas Zachariou, K Nakayama, M. C. Kunkel, P. Nadel-Turonski, Rong Wang, R. De Vita, A. Deur, R. A. Schumacher, Michael Wood, P. Lenisa, W. Phelps, Barry Ritchie, S. Boiarinov, K. Hafidi, G. Ciullo, Y. Prok, Iu. Skorodumina, S Niccolai, P. Eugenio, W. Kim, G. Niculescu, D. S. Carman, W. K. Brooks, I. Bedlinskiy, C. A. Meyer, D. Payette, K. Livingston, Sylvester Joosten, G. Rosner, H. Egiyan, Andrea Celentano, T. B. Hayward, J. Pierce, Jie Zhang, S. Adhikari, Friedrich Klein, D. G. Jenkins, M. Taiuti, K. P. Adhikari, Brian Raue, D. P. Watts, D. Marchand, Y. G. Sharabian, A. Movsisyan, S. Diehl, M. Ripani, C. Salgado, C. Carlin, S. Fegan, M. L. Kabir, A. V. Sarantsev, M. Battaglieri, N. Tyler, B. Duran, V. P. Kubarovsky, E. Voutier, J. A. Tan, U. Shrestha, V. Crede, D. Riser, Chaden Djalali, O. Pogorelko, M. Khachatryan, Michael Dugger, T. Mineeva, H. Avakian, E. Golovatch, A Fradi, R. Dupre, H. Voskanyan, Nikolaos Sparveris, F. Cao, P. Roy, N C Wei, N. K. Walford, R. A. Montgomery, M. Guidal, E. De Sanctis, N. Dashyan, A. Kim, P. Chatagnon, I. J. D. MacGregor, Michael Paolone, M. Holtrop, M. Hattawy, R. W. Gothe, M Ehrhart, K. Hicks, Luciano Pappalardo, S. Park, Taya Chetry, M. Contalbrigo, G. Angelini, Sergey Kuleshov, D. G. Meekins, L. El Fassi, A. I. Ostrovidov, D. G. Ireland, Volker D. Burkert, A. S. Biselli, M. Khandaker, B. McKinnon, D. Heddle, P. L. Cole, M. L. Seely, B. Torayev, Feng Huang, R. Paremuzyan, Sandra K. Johnston, D. Protopopescu, Z. W. Zhao, Nicholas M. Harrison, Gerard Gilfoyle, D. Sokhan, A. Filippi, and C. Munoz Camacho
Subjects: Physics, Photon, Spectrometer, Proton, Linear polarization, media_common.quotation_subject, Nuclear Theory, General Physics and Astronomy, Resonance, Polarization (waves), 01 natural sciences, Asymmetry, Nuclear physics, 0103 physical sciences, Physics::Accelerator Physics, Nuclear Experiment, 010306 general physics, Nucleon, media_common
Abstract: First measurements of double-polarization observables in ω photoproduction off the proton are presented using transverse target polarization and data from the CEBAF Large Acceptance Spectrometer (CLAS) FROST experiment at Jefferson Lab. The beam-target asymmetry F has been measured using circularly polarized, tagged photons in the energy range 1200-2700 MeV, and the beam-target asymmetries H and P have been measured using linearly polarized, tagged photons in the energy range 1200-2000 MeV. These measurements significantly increase the database on polarization observables. The results are included in two partial-wave analyses and reveal significant contributions from several nucleon (N^{*}) resonances. In particular, contributions from new N^{*} resonances listed in the Review of Particle Properties are observed, which aid in reaching the goal of mapping out the nucleon resonance spectrum.
Published: 2019

12. Ξ* photoproduction from threshold to W=3.3GeV

Author: Frank Klein, Dustin Keller, K. Hafidi, E. Golovatch, Y. G. Sharabian, K. Hicks, M. Ripani, C. Bookwalter, K. A. Griffioen, L. Lanza, H. Egiyan, V. Crede, I. J. D. MacGregor, M. Contalbrigo, S. Adhikari, M. Hattawy, C. Munoz Camacho, M. H. Wood, B. McKinnon, I. Bedlinskiy, D. Protopopescu, Michael Dugger, M. Osipenko, L. Elouadrhiri, M. Khachatryan, M. S. Saini, G. Ciullo, P. Eugenio, M. Taiuti, A. El Alaoui, Carlos A. Salgado, F. Cao, W. Kim, I. I. Strakovsky, Maxime Defurne, A. Deur, J. T. Goetz, Y. Prok, D. S. Carman, M. Mirazita, Nikos Sparveris, B. S. Ishkhanov, Nicholas Zachariou, M. L. Kabir, Diane Schott, Michael Paolone, C. A. Meyer, A. I. Ostrovidov, K. Park, X. Wei, N. Gevorgyan, D. I. Glazier, P. Chatagnon, G. V. Fedotov, D. G. Ireland, R. De Vita, M. Guidal, E. Voutier, A. Movsisyan, J. Zhang, F. Sabatié, G. Niculescu, S. Chandavar, V. P. Kubarovsky, Volker D. Burkert, A. S. Biselli, K. Livingston, J. W. Price, A. Celentano, R. W. Gothe, S. Anefalos Pereira, R. Paremuzyan, D. Riser, V. Mokeev, D. P. Weygand, A. Filippi, M. C. Kunkel, Brian Raue, O. Pogorelko, Nicholas M. Harrison, Rong Wang, M. Holtrop, S. Niccolai, R. Dupre, M. Battaglieri, M. Khandaker, Alessandro Rizzo, D. Sokhan, D. I. Sober, L. Guo, M. Ehrhart, M. Ungaro, Pawel Nadel-Turonski, H. Voskanyan, W. J. Briscoe, E. Pasyuk, Iu. Skorodumina, D. Heddle, Taya Chetry, William Brooks, P. L. Cole, Z. W. Zhao, R. A. Schumacher, A. D'Angelo, F. X. Girod, L. El Fassi, S. Strauch, E. L. Isupov, S. Boiarinov, H. Hakobyan, H. S. Jo, S. Diehl, Sylvester Joosten, C. Djalali, J. A. Tan, G. Khachatryan, N. Dashyan, A. Kim, G. Rosner, and Y. Ghandilyan
Subjects: Quark, Physics, Particle physics, 010308 nuclear & particles physics, Nuclear Theory, Quark model, Lattice field theory, 01 natural sciences, Xi baryon, Baryon, Lattice (order), Excited state, 0103 physical sciences, High Energy Physics::Experiment, Gauge theory, Nuclear Experiment, 010306 general physics
Abstract: The doubly strange Xi baryons provide an effective way to study a puzzle called the missing-baryons problem where both quark models and lattice guage theory predict more baryon excited states than are seen experimentally. However, few of these excited states have been observed with any certainty. Here, high-mass Xi* states have been searched for in photoproduction with the detector of the CLAS collaboration, and upper limits for the total cross sections have been established from threshold to W = 3.3 GeV. In addition, the total cross sections of the ground-state Xi(-)(1320) and first excited state Xi(-)(1530) are presented, extending significantly the centre-of-mass energy range of previous data.
Published: 2018

13. Beam-target helicity asymmetry E in K0Λ and K0Σ0 photoproduction on the neutron

Author: P. Lenisa, M. Ungaro, D. G. Ireland, C. A. Meyer, R. Dupre, V. Crede, C.D. Bass, V. A. Nikonov, M. Battaglieri, P. Chatagnon, G. V. Fedotov, R. A. Montgomery, Ron L. Workman, R. Paremuzyan, R. A. Schumacher, C. S. Whisnant, K. P. Adhikari, A. Fradi, M. Osipenko, D. G. Jenkins, Nicholas M. Harrison, N. Markov, Martin K. Mayer, K. A. Griffioen, I. Zonta, I. J. D. MacGregor, A. Kim, H. Hakobyan, M. Khachatryan, D. Sokhan, H. S. Jo, Tim O'Connell, D. Marchand, S. Diehl, M. Bashkanov, B. McKinnon, A. I. Ostrovidov, K. Park, V. Mokeev, G. Khachatryan, L. Lanza, Eberhard Klempt, P. Collins, S. Niccolai, F. X. Girod, M. Contalbrigo, Sandra K. Johnston, P. Eugenio, T. Chetry, Volker D. Burkert, A. S. Biselli, Pawel Nadel-Turonski, M. Mirazita, J. Zhang, Rong Wang, J. W. Price, Alessandro Rizzo, S. Strauch, Iu. Skorodumina, C. Hanretty, George Davey Smith, M. Taiuti, C. Djalali, J. A. Tan, E. Golovatch, Y. G. Sharabian, M. Lowry, G. Charles, K. L. Giovanetti, I. Bedlinskiy, M. Rehfuss, K. Hicks, S. Adhikari, M. L. Kabir, M. Ehrhart, F. Sabatié, Andreas Klein, V. Laine, F. Cao, D. Adikaram, M. Guidal, W. Kim, Larry Weinstein, Z. Akbar, G. Rosner, P. Peng, C. Munoz Camacho, M. H. Wood, M. Hattawy, G. Niculescu, J. A. Fleming, I. I. Strakovsky, M. Holtrop, A. Filippi, A. D'Angelo, M. Ripani, Y. Ghandilyan, Carlos A. Salgado, B. A. Clary, A. M. Sandorfi, B. S. Ishkhanov, M. Khandaker, D. I. Sober, A. Deur, Hong Lu, Michael Paolone, D. Ho, S. Fegan, A. Celentano, R. W. Gothe, D. Heddle, Maxime Defurne, E. L. Isupov, W. Gohn, S. Boiarinov, R. De Vita, T. Kageya, L. El Fassi, N. K. Walford, R. G. Fersch, Frank Klein, P. L. Cole, Z. W. Zhao, Dustin Keller, G. Ciullo, J. P. Ball, Y. Prok, D. S. Carman, Nikos Sparveris, X. Wei, K. Hafidi, E. Voutier, A. Movsisyan, Yordanka Ilieva, L. Barion, V. P. Kubarovsky, D. Riser, A. El Alaoui, Nicholas Zachariou, O. Pogorelko, K. Livingston, H. Voskanyan, D. Protopopescu, W. J. Briscoe, E. Pasyuk, D. P. Watts, H. Egiyan, A. V. Sarantsev, and S. Chandavar
Subjects: Physics, Strange quark, 010308 nuclear & particles physics, media_common.quotation_subject, Nuclear Theory, Quark model, Hyperon, 01 natural sciences, Helicity, Asymmetry, Pseudoscalar meson, Nuclear physics, 13. Climate action, Isospin, 0103 physical sciences, Neutron, Nuclear Experiment, 010306 general physics, media_common
Abstract: We report the first measurements of the E beam-target helicity asymmetry for the γn→K0Λ and K0Σ0 channels in the energy range 1.70≤W≤2.34 GeV. The CLAS system at Jefferson Lab uses a circularly polarized photon beam and a target consisting of longitudinally polarized solid molecular hydrogen deuteride with low background contamination for the measurements. The multivariate analysis method boosted decision trees is used to isolate the reactions of interest. Comparisons with predictions from the KaonMAID, SAID, and Bonn-Gatchina models are presented. These results will help separate the isospin I=0 and I=1 photocoupling transition amplitudes in pseudoscalar meson photoproduction.
Published: 2018

14. Center of Mass Motion of Short-Range Correlated Nucleon Pairs studied via the A(e,e′pp) Reaction

Author: D. Protopopescu, Z. W. Zhao, E. Voutier, M. Duer, D. Marchand, X. Wei, Dustin Keller, P. Eugenio, I. J. D. MacGregor, G. Ciullo, M. Taiuti, C. Djalali, J. A. Tan, W. Kim, Y. Prok, F. Sabatié, L. Lanza, J. P. Ball, D. S. Carman, G. Niculescu, M. L. Kabir, P. Lenisa, S. Strauch, Michael Wood, K. Hafidi, B. A. Clary, K. Livingston, D. G. Jenkins, S. Niccolai, A. Movsisyan, Jie Zhang, Michael Paolone, D. Heddle, A. Celentano, R. W. Gothe, N. Dashyan, Maxime Defurne, H. Avakian, S. E. Kuhn, Friedrich Klein, M. Contalbrigo, A. Beck, Hovanes Egiyan, C. Munoz Camacho, M. Osipenko, M. Ungaro, Eli Piasetzky, H. Voskanyan, R. Fersch, Or Hen, Z. Akbar, L. Barion, R. De Vita, P. Nadel-Turonski, V. Crede, Alessandro Rizzo, Eliahu Cohen, E. Golovatch, R. Dupre, W. J. Briscoe, E. Pasyuk, A. El Alaoui, R. A. Montgomery, R. Paremuzyan, V. Mokeev, M. Battaglieri, M. Ripani, F. Hauenstein, B. S. Ishkhanov, Nicholas M. Harrison, Nicholas Zachariou, Rong Wang, D. Sokhan, Alexander Schmidt, D. P. Watts, S. Adhikari, K. Hicks, B. McKinnon, E. De Sanctis, S. Mey-Tal Beck, A. Kim, V. P. Kubarovsky, Y. G. Sharabian, D. Riser, A. I. Ostrovidov, A. Filippi, P. Rossi, X. Zheng, M. Ehrhart, O. Pogorelko, M. Mirazita, A. Deur, D. G. Ireland, I. Bedlinskiy, M. Khachatryan, M. Khandaker, Nikolaos Sparveris, Volker D. Burkert, A. S. Biselli, M. J. Amaryan, Sandra K. Johnston, K. L. Giovanetti, Larry Weinstein, B. Schmookler, C. A. Meyer, P. Chatagnon, G. V. Fedotov, F. Cao, I. Korover, B. Mustapha, M. Holtrop, Taya Chetry, G. Charles, E. L. Isupov, S. Boiarinov, R. Cruz Torres, H. Hakobyan, S. Diehl, F. X. Girod, J. W. Price, R. A. Schumacher, S. Stepanyan, Avraham Klein, H. S. Jo, A. D'Angelo, L. El Fassi, G. Khachatryan, G. Rosner, Y. Ghandilyan, and K. A. Griffioen
Subjects: Physics, Range (particle radiation), 010308 nuclear & particles physics, Nuclear Theory, General Physics and Astronomy, 01 natural sciences, 7. Clean energy, Momentum, medicine.anatomical_structure, Quantum state, 0103 physical sciences, medicine, Nuclear force, Center of mass, Atomic physics, Nuclear Experiment, 010306 general physics, Nucleon, Nucleus, Fermi Gamma-ray Space Telescope
Abstract: Short-range correlated (SRC) nucleon pairs are a vital part of the nucleus, accounting for almost all nucleons with momentum greater than the Fermi momentum (k_{F}). A fundamental characteristic of SRC pairs is having large relative momenta as compared to k_{F}, and smaller center of mass (c.m.) which indicates a small separation distance between the nucleons in the pair. Determining the c.m. momentum distribution of SRC pairs is essential for understanding their formation process. We report here on the extraction of the c.m. motion of proton-proton (pp) SRC pairs in carbon and, for the first time in heavier and ansymetric nuclei: aluminum, iron, and lead, from measurements of the A(e,e^{'}pp) reaction. We find that the pair c.m. motion for these nuclei can be described by a three-dimensional Gaussian with a narrow width ranging from 140 to 170 MeV/c, approximately consistent with the sum of two mean-field nucleon momenta. Comparison with calculations appears to show that the SRC pairs are formed from mean-field nucleons in specific quantum states.
Published: 2018

15. Measurements of the γvp→p′π+π− cross section with the CLAS detector for 0.4GeV2<Q2<1.0GeV2 and 1.3GeV<W<1.825GeV

Author: Z. W. Zhao, S. Strauch, Whitney Armstrong, M. Battaglieri, K. Park, Volker D. Burkert, H. Hakobyan, R. A. Schumacher, A. S. Biselli, P. Eugenio, T. Mineeva, Barry Ritchie, M. Khandaker, Y. Ilieva, M. Khachatryan, S. Johnston, N. Markov, M. Hattawy, I. Bedlinskiy, Nicholas Zachariou, M. L. Kabir, Maxime Defurne, F. X. Girod, G. Khachatryan, G. Charles, D. G. Ireland, P. Nadel-Turonski, B. A. Clary, Y. Prok, F. Sabatié, X. Wei, R. De Vita, K. Hicks, Michael Paolone, S. Procureur, M. Ungaro, R. A. Montgomery, Sylvester Joosten, M. Osipenko, K. Livingston, J. W. Price, G. Ciullo, J. P. Ball, D. S. Carman, D. Heddle, K. A. Griffioen, I. I. Strakovsky, G. D. Smith, M. Holtrop, S. Niccolai, I. J. D. MacGregor, Jie Zhang, Avraham Klein, Nikos Sparveris, A. Deur, Hovanes Egiyan, C. Munoz Camacho, A. D'Angelo, V. Mokeev, E. De Sanctis, Y. Ghandilyan, N. Dashyan, G. V. Fedotov, A. Celentano, R. W. Gothe, R. Paremuzyan, Taya Chetry, L. Lanza, P. Lenisa, W. K. Brooks, Nicholas M. Harrison, Gerard Gilfoyle, D. I. Sober, M. Ripani, A. Kim, D. Sokhan, G. Gavalian, Y. G. Sharabian, D. G. Jenkins, M. Bashkanov, S. Adhikari, Iu. Skorodumina, B. McKinnon, L. Guo, Sergey Kuleshov, W. Kim, G. Niculescu, E. Golovatch, R. Dupre, L. El Fassi, Alessandro Rizzo, V. Batourine, L. Barion, Friedrich Klein, M. Contalbrigo, N. Tyler, C. Djalali, J. A. Tan, C. Hanretty, H. S. Jo, B. S. Ishkhanov, M. Taiuti, R. G. Fersch, P. L. Cole, C. Salgado, O. Cortes, E. L. Isupov, S. Boiarinov, D. Protopopescu, E. Voutier, I. Balossino, Dustin Keller, Michael Wood, K. Hafidi, H. Avakian, H. Voskanyan, W. J. Briscoe, E. Pasyuk, V. P. Kubarovsky, D. Riser, and O. Pogorelko
Subjects: Physics, Photon, 010308 nuclear & particles physics, Detector, 01 natural sciences, Nuclear physics, Cross section (physics), Reaction model, 0103 physical sciences, High Energy Physics::Experiment, Invariant mass, Nuclear Experiment, 010306 general physics, Nucleon
Abstract: New results on the single-differential and fully integrated cross sections for the process γvp→p′π+π- are presented. The experimental data were collected with the CLAS detector at Jefferson Laboratory. Measurements were carried out in the kinematic region of the reaction invariant mass W from 1.3 to 1.825 GeV and the photon virtuality Q2 from 0.4 to 1.0 GeV2. The cross sections were obtained in narrow Q2 bins (0.05 GeV2) with the smallest statistical uncertainties achieved in double-pion electroproduction experiments to date. The results were found to be in agreement with previously available data where they overlap. A preliminary interpretation of the extracted cross sections, which was based on a phenomenological meson-baryon reaction model, revealed substantial relative contributions from nucleon resonances. The data offer promising prospects to improve knowledge on the Q2 evolution of the electrocouplings of most resonances with masses up to ∼1.8 GeV.
Published: 2018

16. Exclusive photoproduction of π0 up to large values of Mandelstam variables s,t, and u with CLAS

Author: S. Adhikari, S. E. Kuhn, M. Hattawy, P. Eugenio, Taya Chetry, E. Golovatch, M. Taiuti, D. Lersch, M. L. Kabir, E. De Sanctis, Carlos A. Salgado, Michael Paolone, S. Procureur, D. I. Sober, D. Protopopescu, G. V. Fedotov, A. Roy, M. Ripani, M. Khachatryan, D. P. Weygand, R. Dupre, M. Battaglieri, Maxime Defurne, M. C. Kunkel, J. Ritman, F. Cao, M. Guidal, Michael Dugger, G. Gavalian, V. P. Kubarovsky, O. Pogorelko, D. I. Glazier, G. Niculescu, P. Lenisa, A. El Alaoui, Barry Ritchie, Iu. Skorodumina, I. Balossino, D. G. Ireland, V. Crede, Frank Klein, I. Bedlinskiy, K. A. Griffioen, R. De Vita, W. Gohn, V. Mokeev, M. Holtrop, L. Elouadrhiri, Y. G. Sharabian, Andreas Klein, Nicholas Zachariou, G. Mbianda Njencheu, W. Phelps, R. A. Schumacher, Dustin Keller, I. I. Strakovsky, A. Filippi, A. Deur, C. Djalali, R. A. Montgomery, K. Hafidi, V. Batourine, H. Avakian, J. A. Tan, L. Lanza, A. D'Angelo, D. P. Watts, D. G. Jenkins, H. Voskanyan, K. Livingston, F. Sabatié, H. Egiyan, M. Khandaker, S. Niccolai, J. Zhang, S. Bültmann, W. J. Briscoe, E. Pasyuk, Alessandro Rizzo, L. El Fassi, J. W. Price, C. E. Hyde, F. X. Girod, L. Guo, M. Ungaro, T. Mineeva, R. G. Fersch, Pawel Nadel-Turonski, P. L. Cole, Z. W. Zhao, K. Hicks, Laura Clark, W. Kim, K. Joo, S. Strauch, G. Charles, B. S. Ishkhanov, O. Cortes, G. Ciullo, E. L. Isupov, J. P. Ball, Y. Prok, D. S. Carman, D. Payette, M. Osipenko, S. Boiarinov, Nikos Sparveris, X. Wei, I. J. D. MacGregor, K. P. Adhikari, A. Kim, E. Voutier, A. Movsisyan, N. Dashyan, H. Hakobyan, S. Stepanyan, L. Barion, M. J. Amaryan, K. L. Giovanetti, Larry Weinstein, G. Khachatryan, S. Schadmand, William Brooks, G. Rosner, S. Ghosh, Y. Ghandilyan, P. V. Degtyarenko, A. Celentano, R. W. Gothe, M. Contalbrigo, C. Munoz Camacho, J. Poudel, B. McKinnon, J. M. Laget, Nicholas M. Harrison, Gerard Gilfoyle, D. Sokhan, A. Fradi, N. Markov, A. I. Ostrovidov, K. Park, G. R. Goldstein, Volker D. Burkert, and A. S. Biselli
Subjects: Quark, Quantum chromodynamics, Physics, Meson, 010308 nuclear & particles physics, Perturbative QCD, Parton, Mandelstam variables, Photon energy, 01 natural sciences, Nuclear physics, 0103 physical sciences, High Energy Physics::Experiment, Sum rule in quantum mechanics, 010306 general physics
Abstract: Exclusive photoproduction cross sections have been measured for the process γ p → p π 0 [ e + e − ( γ ) ] with the Dalitz decay final state using tagged photon energies in the range of E γ = 1.275 – 5.425 GeV. The complete angular distribution of the final state π 0 , for the entire photon energy range up to large values of t and u , has been measured for the first time. The data obtained show that the cross section d σ / d t , at mid to large angles, decreases with energy as s − 6.89 ± 0.26 . This is in agreement with the perturbative QCD quark counting rule prediction of s − 7 . Paradoxically, the size of angular distribution of measured cross sections is greatly underestimated by the QCD-based generalized parton distribution mechanism at highest available invariant energy s = 11 GeV 2 . At the same time, the Regge-exchange-based models for π 0 photoproduction are more consistent with experimental data.
Published: 2018

17. Measurement of the beam asymmetry Σ and the target asymmetry T in the photoproduction of ω mesons off the proton using CLAS at Jefferson Laboratory

Author: William Brooks, George Davey Smith, R. A. Schumacher, A. El Alaoui, S. Stepanyan, J. Pierce, H. Y. Lu, P. Eugenio, G. Gavalian, I. Denisenko, N. Dashyan, Taya Chetry, M. Taiuti, A. Filippi, A. Fradi, D. P. Watts, K. A. Griffioen, Friedrich Klein, V. Crede, M. Khandaker, D. G. Meekins, Brian Raue, A. D'Angelo, A. V. Sarantsev, Yordanka Ilieva, Nicholas Zachariou, E. Pasyuk, V. Mokeev, V. Batourine, R. Paremuzyan, R. De Vita, N. Markov, L. Lanza, G. Rosner, E. Golovatch, K. Hicks, W. Kim, Sergey Kuleshov, M. Ripani, R. A. Montgomery, F. Sabatié, S. Niccolai, Carlos A. Salgado, C. D. Keith, Pawel Nadel-Turonski, D. G. Jenkins, Eberhard Klempt, B. A. Clary, J. Brock, Alessandro Rizzo, R. Dupre, M. Battaglieri, J. Zhang, C. Djalali, J. A. Tan, L. El Fassi, J. W. Price, S. Anefalos Pereira, K. Livingston, C. Hanretty, C. Carlin, M. Guidal, L. Guo, M. Ungaro, Gerard Gilfoyle, A. I. Ostrovidov, A. V. Anisovich, K. Park, G. Charles, G. Niculescu, V. A. Nikonov, G. Ciullo, J. P. Ball, B. Torayev, Y. Prok, F. X. Girod, M. E. McCracken, D. S. Carman, D. G. Ireland, M. Holtrop, K. Joo, I. Bedlinskiy, V. P. Kubarovsky, D. Riser, M. Osipenko, Andreas Klein, Nikos Sparveris, X. Wei, T. Mineeva, D. Sokhan, O. Pogorelko, S. Procureur, W. Gohn, A. Kim, Z. E. Meziani, W. Phelps, Volker D. Burkert, M. Bashkanov, A. S. Biselli, B. S. Ishkhanov, L. Elouadrhiri, K. L. Giovanetti, I. Balossino, S. Strauch, Michael Dugger, D. I. Sober, E. Voutier, I. I. Strakovsky, A. Movsisyan, B. McKinnon, Dustin Keller, S. Park, A. Deur, K. Hafidi, Iu. Skorodumina, Sylvester Joosten, S. Fegan, G. Khachatryan, P. L. Cole, Z. W. Zhao, E. Phelps, N. Gevorgyan, D. Protopopescu, W. J. Briscoe, C. Munoz Camacho, M. H. Wood, A. Celentano, R. W. Gothe, M. Contalbrigo, Z. Akbar, N. K. Walford, I. J. D. MacGregor, S. Adhikari, M. Hattawy, Martin K. Mayer, Y. G. Sharabian, C. Gleason, Barry Ritchie, P. Roy, C. A. Meyer, G. V. Fedotov, E. L. Isupov, S. Boiarinov, K. P. Adhikari, H. Hakobyan, and P. Lenisa
Subjects: Physics, Particle physics, Proton, Meson, 010308 nuclear & particles physics, Partial wave analysis, media_common.quotation_subject, Nuclear Theory, Bremsstrahlung, Observable, 7. Clean energy, 01 natural sciences, Resonance (particle physics), Asymmetry, Baryon, Nuclear physics, 13. Climate action, 0103 physical sciences, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, media_common
Abstract: The photoproduction of ω mesons off the proton has been studied in the reaction γp→pω using the CEBAF Large Acceptance Spectrometer (CLAS) and the frozen-spin target in Hall B at the Thomas Jefferson National Accelerator Facility. For the first time, the target asymmetry T has been measured in photoproduction from the decay ω→π+π-π0, using a transversely polarized target with energies ranging from just above the reaction threshold up to 2.8 GeV. Significant nonzero values are observed for these asymmetries, reaching about 30-40% in the third-resonance region. New measurements for the photon-beam asymmetry Σ are also presented, which agree well with previous CLAS results and extend the world database up to 2.1 GeV. These data and additional ω photoproduction observables from CLAS were included in a partial-wave analysis within the Bonn-Gatchina framework. Significant contributions from s-channel resonance production were found in addition to t-channel exchange processes.
Published: 2018

18. Measurement of the helicity asymmetry E in ω→π+π−π0 photoproduction

Author: M. Contalbrigo, T. Mineeva, R. A. Schumacher, Z. Akbar, M. Khachatryan, V. Mokeev, Taya Chetry, A. V. Anisovich, G. Ciullo, J. P. Ball, Y. Prok, D. S. Carman, E. Golovatch, F. Cao, P. Roy, M. Guidal, B. S. Ishkhanov, K. Hicks, C. Gleason, Iu. Skorodumina, Nikos Sparveris, X. Wei, M. Holtrop, O. Cortes, K. P. Adhikari, C. D. Keith, E. L. Isupov, M. Ripani, Barry Ritchie, E. Voutier, Nicholas Zachariou, S. Stepanyan, Laura Clark, L. Guo, H. Egiyan, S. Boiarinov, G. Khachatryan, A. Movsisyan, I. J. D. MacGregor, E. De Sanctis, G. Charles, J. Brock, Sylvester Joosten, M. Hattawy, Carlos A. Salgado, A. Celentano, R. W. Gothe, A. V. Sarantsev, S. Park, M. Osipenko, F. Sabatié, W. J. Briscoe, I. I. Strakovsky, Y. G. Sharabian, S. Niccolai, M. Ungaro, D. I. Sober, A. I. Ostrovidov, K. Park, Michael Paolone, R. Dupre, M. Battaglieri, C. Munoz Camacho, A. Filippi, G. V. Fedotov, A. Deur, K. A. Griffioen, V. Crede, D. G. Ireland, W. Phelps, Lorenzo Zana, S. Adhikari, N. Dashyan, D. Protopopescu, Alessandro Rizzo, M. Garçon, Volker D. Burkert, B. McKinnon, W. K. Brooks, D. G. Jenkins, I. Bedlinskiy, V. A. Nikonov, Brian Raue, P. Nadel-Turonski, A. Fradi, F. X. Girod, W. Kim, I. Denisenko, V. Batourine, Michael Dugger, G. Rosner, N. Markov, R. Paremuzyan, S. Strauch, Andreas Klein, K. Livingston, W. Gohn, R. De Vita, C. Carlin, Nicholas M. Harrison, S. Anefalos Pereira, L. Lanza, D. Sokhan, A. Kim, C. Djalali, C. Hanretty, R. Fersch, H. Avakian, Eberhard Klempt, J. Zhang, H. Voskanyan, E. Pasyuk, J. W. Price, George Davey Smith, V. P. Kubarovsky, D. G. Meekins, A. D'Angelo, O. Pogorelko, Frank Klein, Dustin Keller, L. El Fassi, Michael Wood, K. Hafidi, P. L. Cole, Z. W. Zhao, P. Eugenio, M. Taiuti, N. Gevorgyan, D. Heddle, G. Hollis, Hrachya Hakobyan, M. J. Amaryan, K. L. Giovanetti, and M. Khandaker
Subjects: Physics, Meson, 010308 nuclear & particles physics, Partial wave analysis, Bremsstrahlung, Resonance, Observable, 01 natural sciences, Helicity, Nuclear physics, Pomeron, 0103 physical sciences, Nuclear Experiment, 010306 general physics, Nucleon
Abstract: The double-polarization observable E was studied for the reaction γp → pω using the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B at the Thomas Jefferson National Accelerator Facility and the longitudinally polarized frozen-spin target (FROST). The observable was measured from the charged decay mode of the meson, ω → π+π−π0, using a circularly polarized tagged-photon beam with energies ranging from the ω threshold at 1.1 to 2.3 GeV. A partial-wave analysis within the Bonn-Gatchina framework found dominant contributions from the 3/2+ partial wave near threshold, which is identified with the subthreshold N(1720) 3/2+ nucleon resonance. To describe the entire data set, which consisted of ω differential cross sections and a large variety of polarization observables, further contributions from other nucleon resonances were found to be necessary. With respect to nonresonant mechanisms, π exchange in the t channel was found to remain small across the analyzed energy range, while Pomeron t-channel exchange gradually grew from the reaction threshold to dominate all other contributions above W ≈ 2 GeV.
Published: 2017

19. 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

20. 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

21. 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

22. 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

23. Beam-Target Helicity Asymmetry for γ→n→→π−p in the N* Resonance Region

Author: C. Gleason, Barry Ritchie, G. V. Fedotov, K. P. Adhikari, J. Ball, M. Hattawy, D. P. Watts, Marco Ripani, H. Hakobyan, G. Rosner, S. Fegan, F. X. Girod, M. Ungaro, K. A. Griffioen, I. I. Strakovsky, K. Livingston, R. Paremuzyan, C. Djalali, X. Wei, A. V. Sarantsev, A. Deur, L. Elouadrhiri, Y. Ghandilyan, R. A. Schumacher, Nicholas M. Harrison, Gerard Gilfoyle, Z. Akbar, V. Crede, L. Lanza, D. I. Glazier, M. Osipenko, Jie Zhang, E. Pasyuk, G. Khachatryan, R. A. Montgomery, P. Lenisa, P. L. Cole, G. Ciullo, D. Sokhan, N. Markov, D. S. Carman, W. Phelps, V. P. Kubarovsky, D. Riser, P. Eugenio, L. Clark, M. Bashkanov, V. Laine, O. Pogorelko, W. J. Briscoe, F. J. Klein, S. Niccolai, R. Fersch, S. M. Hughes, B. McKinnon, Nikolaos Sparveris, A. Movsisyan, M. M. Lowry, I. Zonta, R. De Vita, N. Dashyan, H. S. Jo, C. Salgado, Avraham Klein, Ron L. Workman, F. Sabatié, I. Bedlinskiy, L. Colaneri, Andrea Celentano, C. Bass, Dustin Keller, H. Y. Lu, Yordanka Ilieva, E. Golovatch, S. Strauch, N. K. Walford, R. Dupre, G. Charles, Alfred Švarc, S. Procureur, L. El Fassi, Victor Mokeev, Z. W. Zhao, J. A. Fleming, J. W. Price, D. Ho, Michael Wood, T. Kageya, A. M. Sandorfi, Y. G. Sharabian, Taya Chetry, S. Anefalos Pereira, I. J. D. MacGregor, W. Kim, P. Collins, G. Niculescu, V. A. Nikonov, A. D'Angelo, R. W. Gothe, C. S. Whisnant, E. L. Isupov, M. Battaglieri, Ye Tian, H. Voskanyan, A. Fradi, K. Joo, K. Hicks, E. De Sanctis, V. Batourine, D. A. Jenkins, Sergey Kuleshov, D. G. Ireland, H. Jiang, C. S. Nepali, P. Peng, K. Park, D. I. Sober, Volker D. Burkert, C. Munoz Camacho, A. S. Biselli, Tim O'Connell, Eberhard Klempt, B. S. Ishkhanov, D. Adikaram, T. Mineeva, M. Guidal, L. Guo, Alessandro Rizzo, S. Joosten, G. D. Smith, M. Holtrop, D. Protopopescu, C. Hanretty, A. Kim, W. Gohn, E. Voutier, A. El Alaoui, Nicholas Zachariou, B. Torayev, M. J. Amaryan, H. Avakian, M. Contalbrigo, M. Khandaker, A. Filippi, M. Paolone, Iu. Skorodumina, and G. Murdoch
Subjects: Physics, Photon, 010308 nuclear & particles physics, General Physics and Astronomy, 7. Clean energy, 01 natural sciences, Helicity, Nuclear physics, Deuterium, Solid hydrogen, Isospin, 0103 physical sciences, Neutron, Invariant mass, Nuclear Experiment, 010306 general physics, Nucleon
Abstract: We report the first beam-target double-polarization asymmetries in the γ þ nðpÞ → π− þ pðpÞ reaction spanning the nucleon resonance region from invariant mass W ¼ 1500 to 2300 MeV. Circularly polarized photons and longitudinally polarized deuterons in solid hydrogen deuteride (HD) have been used with the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. The exclusive final state has been extracted using three very different analyses that show excellent agreement, and these have been used to deduce the E polarization observable for an effective neutron target. These results have been incorporated into new partial wave analyses and have led to significant revisions for several γnN* resonance photocouplings.
Published: 2017

24. 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

25. Target and beam-target spin asymmetries in exclusive pion electroproduction for Q2>1 GeV2 . II. ep→eπ0p

Author: G. Murdoch, I. Zonta, D. Heddle, G. Hollis, R. A. Schumacher, S. Koirala, F. Sabatié, E. Golovatch, K. A. Griffioen, G. Charles, S. Niccolai, E. De Sanctis, I. Balossino, C. Djalali, Alessandro Rizzo, Frank Klein, G. V. Fedotov, B. Torayev, Dustin Keller, Taya Chetry, D. P. Watts, H. Egiyan, G. Ciullo, J. P. Ball, Y. Prok, T. Mineeva, D. S. Carman, T. A. Forest, D. G. Jenkins, C. Hanretty, G. Rosner, P. Lenisa, S. Stepanyan, L. Elouadrhiri, L. Lanza, Igor Strakovsky, Nikos Sparveris, A. Filippi, X. Wei, K. Hafidi, Y. Ghandilyan, H. Y. Lu, P. Stoler, E. Fanchini, M. Khandaker, A. Deur, Michael Paolone, E. Voutier, I. Bedlinskiy, A. Movsisyan, H. Avakian, D. G. Ireland, P. Bosted, P. Roy, V. Crede, P. Eugenio, M. Taiuti, D. Adikaram, Brian Raue, M. J. Amaryan, M. Osipenko, N. Dashyan, M. Guidal, R. Dupre, M. Battaglieri, F. X. Girod, D. I. Glazier, A. Kim, K. Hicks, G. Niculescu, E. Seder, R. A. Montgomery, H. Voskanyan, S. Bültmann, I. Stankovic, R. De Vita, M. Holtrop, W. J. Briscoe, E. Pasyuk, I. J. D. MacGregor, J. Zhang, Y. G. Sharabian, Iu. Skorodumina, A. Ni, W. Gohn, J. W. Price, Larry Weinstein, W. Kim, William Brooks, M. Ripani, S. Chandavar, S. Strauch, G. Khachatryan, S. Anefalos Pereira, S. Fegan, S. E. Kuhn, Laura Clark, M. Hattawy, L. Guo, M. Ungaro, S. M. Hughes, J. A. Fleming, V. P. Kubarovsky, W. Phelps, O. Cortes, V. Mokeev, E. L. Isupov, O. Pogorelko, A Klei, Ye Tian, P. Rossi, Andrew Puckett, S. Boiarinov, Martin K. Mayer, K. Joo, K. P. Adhikari, M. S. Saini, H. Hakobyan, H. S. Jo, M. Contalbrigo, Z. Akbar, M. E. McCracken, P. Nadel-Turonski, R. A. Badui, George Davey Smith, A. D'Angelo, A. Celentano, R. W. Gothe, L. El Fassi, N. K. Walford, R. G. Fersch, T. Cao, P. L. Cole, Z. W. Zhao, K. Livingston, N. Guler, D. Protopopescu, A. El Alaoui, Nicholas Zachariou, A. I. Ostrovidov, K. Park, B. McKinnon, H. Jiang, M. Mirazita, Volker D. Burkert, A. S. Biselli, C. Munoz Camacho, R. Paremuzyan, Nicholas M. Harrison, Gerard Gilfoyle, D. Sokhan, L. Colaneri, A. Fradi, N. Markov, and S. Pisano
Subjects: Physics, Particle physics, 010308 nuclear & particles physics, Scattering, Resonance, Electron, 01 natural sciences, Nuclear physics, Pion, Amplitude, 0103 physical sciences, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, Nucleon, Sign (mathematics), Spin-½
Abstract: Beam-target double-spin asymmetries and target single-spin asymmetries were measured for the exclusive pi(0) electroproduction reaction. gamma(*) p -> p pi(0), expanding an analysis of the. gamma(*) p -> n pi(+) 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 GeV2. Results were obtained for about 5700 bins in W, Q(2), cos(theta(*)), and phi(*). The beam-target asymmetries were found to generally be greater than zero, with relatively modest phi(*) dependence. The target asymmetries exhibit very strong phi(*) dependence, with a change in sign occurring between results at low W and high W, in contrast to pi(+) electroproduction. Reasonable agreement is found with phenomenological fits to previous data for W < 1.6 GeV, but significant differences are seen at higherW. When combined with cross-sectional measurements, as well as pi(+) 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

26. 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

27. 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

28. 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

29. 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

30. 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

31. Determination of the beam-spin asymmetry of deuteron photodisintegration in the energy regionEγ=1.1–2.3 GeV

Author: Alessandra Filippi, Reinhard Schumacher, Eugene Pasyuk, Alessandro Rizzo, Nicholas Zachariou, Philip Cole, Annalisa D'Angelo, Marco Contalbrigo, Franck Sabatie, Andrea Celentano, David Ireland, Mikhail Osipenko, Nikolay Markov, Marco Battaglieri, Eric Voutier, Irene Zonta, Ian MacGregor, Gabriel Charles, and Evgeny Isupov
Subjects: Quantum chromodynamics, Physics, Nuclear and High Energy Physics, Particle physics, Proton, media_common.quotation_subject, Hadron, Bremsstrahlung, Perturbative QCD, 7. Clean energy, Asymmetry, Particle identification, Nuclear physics, Photodisintegration, Physics::Accelerator Physics, High Energy Physics::Experiment, Nuclear Experiment, media_common
Abstract: The beam-spin asymmetry, Σ, for the reaction γd→pn has been measured using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility (JLab) for six photon-energy bins, between 1.1 and 2.3 GeV, and proton angles in the center-of-mass frame, θc.m., between 25∘ and 160∘. These are the first measurements of beam-spin asymmetries at θc.m.=90∘ for photon-beam energies above 1.6 GeV, and the first measurements for angles other than θc.m.=90∘. The angular and energy dependence of Σ is expected to aid in the development of QCD-based models to understand the mechanisms of deuteron photodisintegration in the transition region between hadronic and partonic degrees of freedom, where both effective field theories and perturbative QCD cannot make reliable predictions.
Published: 2015

32. Measurements ofep→e′π+nat1.6<W<2.0 GeV and extraction of nucleon resonance electrocouplings at CLAS

Author: B. S. Ishkhanov, I. Zonta, J. Bono, P. Nadel-Turonski, X. Wei, E. De Sanctis, P. Eugenio, M. Taiuti, K. A. Griffioen, B. Garillon, Z. W. Zhao, C. E. Hyde, A. Filippi, D. Protopopescu, A. Kim, M. Garçon, S. Niccolai, A. Trivedi, Andrew Puckett, J. T. Goetz, F. X. Girod, Michael Paolone, I. I. Strakovsky, V. Crede, L. Guo, R. A. Schumacher, Sergey Kuleshov, M. Khandaker, Alessandro Rizzo, S. Chandavar, W. Tang, G. Charles, A. Deur, M. Osipenko, Latifa Elouadrhiri, Gerard Gilfoyle, Nikolaos Sparveris, M. Battaglieri, W. K. Brooks, A. Simonyan, R. De Vita, R. A. Montgomery, D. Martinez, B. Guegan, H. Hakobyan, C. Hanretty, C. E. Taylor, K. Livingston, N. Dashyan, G. V. Fedotov, S. Strauch, V. Sytnik, E. Golovatch, R. Dupre, Avraham Klein, H. S. Jo, Jie Zhang, S. Anefalos Pereira, V. Mokeev, P. Lenisa, V. P. Kubarovsky, H. S. Joo, H. Y. Lu, W. Phelps, Eugene Pasyuk, Inna Aznauryan, O. Pogorelko, S. M. Hughes, K. P. Adhikari, I. Bedlinskiy, C. Salgado, P. Roy, S. E. Kuhn, P. Peng, Hovanes Egiyan, C. Munoz Camacho, W. Kim, J. A. Fleming, M. Guidal, G. Niculescu, Yordanka Ilieva, H. Avakian, C. Djalali, K. Park, M. Ripani, I. Niculescu, B. McKinnon, P. Rossi, M. J. Amaryan, S. Joosten, G. D. Smith, M. Holtrop, Friedrich Klein, A. El Alaoui, M. Hattawy, Brian Raue, L. Zana, G. Rosner, H. Voskanyan, Nicholas Zachariou, Elton Smith, D. G. Jenkins, W. J. Briscoe, E. Seder, F. Sabatié, P. Stoler, D. P. Watts, S. Procureur, H. Moutarde, Dustin Keller, M. Ungaro, Michael Wood, K. Hicks, Y. G. Sharabian, K. Joo, O. Cortes, E. L. Isupov, Ye Tian, J. W. Price, K. L. Giovanetti, S. Fegan, Iu. Skorodumina, Larry Weinstein, D. Doughty, Y. Prok, D. S. Carman, E. Voutier, M. Contalbrigo, R. A. Badui, A. Celentano, R. W. Gothe, N. K. Walford, J. J. Phillips, I. J. D. MacGregor, A. D'Angelo, L. El Fassi, R. G. Fersch, Diane Schott, P. L. Cole, A. I. Ostrovidov, N. Gevorgyan, D. G. Ireland, H. Jiang, Volker D. Burkert, A. S. Biselli, L. Colaneri, N. Markov, and S. Pisano
Subjects: Physics, Quark, Nuclear and High Energy Physics, Particle physics, Amplitude, Isospin, Quark model, Isobar, Resonance, Invariant mass, Nucleon
Abstract: Differential cross sections of the exclusive process $ep\ensuremath{\rightarrow}{e}^{\ensuremath{'}}{\ensuremath{\pi}}^{+}n$ were measured with good precision in the range of the photon virtuality ${Q}^{2}=1.8--4.5$ ${\mathrm{GeV}}^{2}$ and the invariant mass range of the ${\ensuremath{\pi}}^{+}n$ final state $W=1.6--2.0$ GeV using the Continuous Electron Beam Accelerator Facility Large Acceptance Spectrometer. Data were collected with nearly complete coverage in the azimuthal and polar angles of the $n{\ensuremath{\pi}}^{+}$ center-of-mass system. More than 37 000 cross-section points were measured. The contributions of the isospin $I=\frac{1}{2}$ resonances $N(1675){\frac{5}{2}}^{\ensuremath{-}},N(1680){\frac{5}{2}}^{+}$, and $N(1710){\frac{1}{2}}^{+}$ were extracted at different values of ${Q}^{2}$ using a single-channel, energy-dependent resonance amplitude analysis. Two different approaches, the unitary isobar model and the fixed-$t$ dispersion relations, were employed in the analysis. We observe significant strength of the $N(1675){\frac{5}{2}}^{\ensuremath{-}}$ in the ${A}_{1/2}$ amplitude, which is in strong disagreement with quark models that predict both transverse amplitudes to be strongly suppressed. For the $N(1680){\frac{5}{2}}^{+}$ we observe a slow changeover from the dominance of the ${A}_{3/2}$ amplitude at the real photon point $({Q}^{2}=0)$ to a ${Q}^{2}$ where ${A}_{1/2}$ begins to dominate. The scalar amplitude ${S}_{1/2}$ drops rapidly with ${Q}^{2}$ consistent with quark model prediction. For the $N(1710){\frac{1}{2}}^{+}$ resonance our analysis shows significant strength for the ${A}_{1/2}$ amplitude at ${Q}^{2}l2.5$ ${\mathrm{GeV}}^{2}$.
Published: 2015

33. Strangeness Suppression ofqq¯Creation Observed in Exclusive Reactions

Author: V. Sytnik, M. Ungaro, R. Paremuzyan, Gerard Gilfoyle, S. Chandavar, K. Livingston, D. Sokhan, B. McKinnon, M. Aghasyan, M. Mirazita, V. Batourine, M. Battaglieri, I. Zonta, M. Garçon, X. Wei, K. Joo, Jie Zhang, C. E. Hyde, E. Golovatch, S. Koirala, P. Peng, C. Munoz Camacho, J. Ball, D. S. Carman, Diane Schott, A. I. Ostrovidov, K. Park, R. A. Schumacher, M. Khandaker, V. Crede, S. Strauch, Victor Mokeev, S. Niccolai, D. G. Ireland, A. Movsisyan, Latifa Elouadrhiri, C. Djalali, H. Jiang, D. P. Watts, Volker D. Burkert, A. S. Biselli, C. A. Meyer, N. K. Walford, A. V. Vlassov, H. Voskanyan, A. Kim, W. I. Levine, J. A. Fleming, G. V. Fedotov, H. Hakobyan, C. Hanretty, T. A. Forest, Sergey Kuleshov, P. L. Cole, E. Voutier, R. A. Montgomery, W. J. Briscoe, C. I. Moody, R. De Vita, P. Lenisa, P. Eugenio, K. P. Adhikari, M. D. Mestayer, D. Protopopescu, N. Dashyan, P. Roy, Andrew Puckett, O. Cortes, F. X. Girod, I. Bedlinskiy, Ye Tian, Martin K. Mayer, K. L. Giovanetti, B. Garillon, J. W. Price, S. Pozdniakov, S. Boiarinov, M. Guidal, R. Dupre, H. Y. Lu, L. Colaneri, A. Simonyan, Larry Weinstein, S. Anefalos Pereira, Brian Raue, M. S. Saini, F. Sabatié, Z. W. Zhao, K. A. Griffioen, D. Doughty, M. Holtrop, A. D'Angelo, H. S. Jo, A. El Alaoui, J. T. Goetz, L. El Fassi, Luciano Pappalardo, M. Hattawy, Y. Ilieva, G. Charles, A. Deur, S. Pisano, Nicholas Zachariou, W. K. Brooks, V. P. Kubarovsky, P. Nadel-Turonski, G. Rosner, D. Rimal, I. Niculescu, O. Pogorelko, S. M. Hughes, Y. Ghandilyan, H. Moutarde, B. Guegan, M. Ripani, Dustin Keller, B. Vernarsky, Michael Wood, Alessandro Rizzo, W. Phelps, W. Tang, M. Osipenko, W. Kim, G. Niculescu, I. J. D. MacGregor, A. Celentano, R. W. Gothe, and M. Contalbrigo
Subjects: Physics, Quark, Particle physics, High energy, Meson production, Proton, 010308 nuclear & particles physics, High Energy Physics::Lattice, High Energy Physics::Phenomenology, Nuclear Theory, General Physics and Astronomy, Strangeness, 01 natural sciences, Hadronization, Nuclear physics, 0103 physical sciences, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics
Abstract: In this study, we measured the ratios of electroproduction cross sections from a proton target for three exclusive meson-baryon final states: ΛK+, pπ0, and nπ+, with the CLAS detector at Jefferson Lab. Using a simple model of quark hadronization, we extract qq¯ creation probabilities for the first time in exclusive two-body production, in which only a single qq¯ pair is created. We observe a sizable suppression of strange quark-antiquark pairs compared to nonstrange pairs, similar to that seen in high-energy production.
Published: 2014

34. 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

35. 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

36. 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

37. 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

38. 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

39. Beam asymmetryΣforπ+andπ0photoproduction on the proton for photon energies from 1.102 to 1.862 GeV

Author: C. Hanretty, I. Bedlinskiy, Martin K. Mayer, Ron L. Workman, G. Rosner, M. S. Saini, O. Cortes, E. L. Isupov, Ye Tian, Sergey Kuleshov, B. S. Ishkhanov, S. Boiarinov, F. X. Girod, S. Strauch, E. De Sanctis, A. El Alaoui, Y. Ilieva, D. P. Watts, H. Egiyan, M. Aghasyan, Nicholas Zachariou, I. Zonta, D. I. Sober, P. Nadel-Turonski, D. Rimal, Friedrich Klein, Brian Raue, J. W. Price, C. Munoz Camacho, M. Contalbrigo, G. V. Fedotov, S. Chandavar, Michael Dugger, K. Joo, Yakov I. Azimov, K. P. Adhikari, D. P. Weygand, S. S. Stepanyan, S. Niccolai, H. Seraydaryan, M. Taiuti, W. Tang, Y. G. Sharabian, A. Kubarovsky, R. Dupre, N. A. Baltzell, M. Battaglieri, M. Osipenko, M. Ripani, F. Sabatié, George Davey Smith, T. Mineeva, P. Eugenio, D. Martinez, D. G. Ireland, V. Crede, K. Livingston, S. Koirala, E. Seder, I. I. Strakovsky, I. J. D. MacGregor, R. A. Montgomery, D. Adikaram, M. Guidal, M. Khandaker, A. Deur, A. D'Angelo, V. Mokeev, M. Holtrop, J. T. Goetz, J. A. Fleming, R. De Vita, Barry Ritchie, Luciano Pappalardo, M. J. Amaryan, L. El Fassi, C. Djalali, Lorenzo Zana, P. Collins, N. K. Walford, E. Golovatch, H. Hakobyan, H. Moutarde, H. S. Jo, J. J. Phillips, S. Park, E. Voutier, S. Anefalos Pereira, Z. W. Zhao, C. Salgado, P. Rossi, K. L. Giovanetti, J. Zhang, D. Ho, W. Kim, D. Doughty, K. A. Griffioen, G. Niculescu, D. Heddle, V. P. Kubarovsky, H. Y. Lu, W. Gohn, O. Pogorelko, S. Lewis, P. L. Cole, C. S. Nepali, B. Torayev, D. Protopopescu, Dustin Keller, S. Pozdniakov, I. Niculescu, S. Procureur, K. Hafidi, A. Celentano, R. W. Gothe, R. A. Schumacher, E. Munevar, Avraham Klein, H. Avakian, H. Voskanyan, W. J. Briscoe, E. Pasyuk, P. Stoler, K. Hicks, S. Tkachenko, L. Guo, N. Harrison, S. Pisano, Diane Schott, A. I. Ostrovidov, K. Park, Volker D. Burkert, A. S. Biselli, N. Dashyan, S. Fegan, R. Paremuzyan, Gerard Gilfoyle, J. P. Ball, Y. Prok, D. S. Carman, D. Sokhan, B. McKinnon, M. Mirazita, E. Phelps, N. Gevorgyan, and V. Batourine
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, Photon, Proton, 010308 nuclear & particles physics, Scattering, media_common.quotation_subject, Partial wave analysis, 01 natural sciences, 7. Clean energy, Asymmetry, Nuclear physics, Pion, 0103 physical sciences, Nuclear Experiment, 010306 general physics, Energy (signal processing), Beam (structure), media_common
Abstract: Beam asymmetries for the reactions $\ensuremath{\gamma}p\ensuremath{\rightarrow}p{\ensuremath{\pi}}^{0}$ and $\ensuremath{\gamma}p\ensuremath{\rightarrow}n{\ensuremath{\pi}}^{+}$ have been measured with the CEBAF Large Acceptance Spectrometer (CLAS) and a tagged, linearly polarized photon beam with energies from 1.102--1.862 GeV. A Fourier moment technique for extracting beam asymmetries from experimental data is described. The results reported here possess greater precision and finer energy resolution than previous measurements. Our data for both pion reactions appear to favor the SAID and Bonn-Gatchina scattering analyses over the older Mainz MAID predictions. After incorporating the present set of beam asymmetries into the world database, exploratory fits made with the SAID analysis indicate that the largest changes from previous fits are for properties of the $\ensuremath{\Delta}(1700)3/{2}^{\ensuremath{-}}$ and $\ensuremath{\Delta}(1905)5/{2}^{+}$ states.
Published: 2013

40. Differential photoproduction cross sections of theΣ0(1385),Λ(1405), andΛ(1520)

Author: H. Y. Lu, Jie Zhang, H. Avakian, M. F. Vineyard, R. Fersch, N. Guler, M. J. Amaryan, N. K. Walford, S. Fegan, H. Voskanyan, H. Seraydaryan, J. P. Ball, D. S. Carman, I. Zonta, R. De Vita, W. J. Briscoe, E. Pasyuk, E. Voutier, Friedrich Klein, H. Moutarde, I. Niculescu, Brian Raue, K. L. Giovanetti, Y. G. Sharabian, A. Kubarovsky, S. Anefalos Pereira, Larry Weinstein, A. Deur, R. A. Schumacher, F. Sabatié, B. Vernarsky, V. P. Kubarovsky, D. Doughty, S. Tkachenko, P. Eugenio, L. Guo, G. Niculescu, Andrew Puckett, Martin K. Mayer, O. Pogorelko, D. Adikaram, W. K. Brooks, D. Heddle, D. Protopopescu, M. Guidal, S. Pozdniakov, S. Park, E. Munevar, S. Niccolai, S. Chandavar, E. Seder, B. S. Ishkhanov, E. De Sanctis, C. E. Taylor, J. J. Phillips, P. Rossi, M. S. Saini, Michael Wood, M. Aghasyan, Z. W. Zhao, David M. Keller, D. I. Sober, M. Holtrop, S. Stepanyan, I. J. D. MacGregor, H. Hakobyan, D. Ho, V. Crede, Y. Ilieva, Kei Moriya, C. A. Meyer, G. V. Fedotov, E. Golovatch, C. Hanretty, Nicholas Zachariou, M. Khandaker, M. Contalbrigo, C. S. Nepali, Luciano Pappalardo, S. Strauch, D. P. Watts, R. A. Montgomery, S. Lewis, M. D. Mestayer, B. McKinnon, J. A. Fleming, O. Cortes, T. Mineeva, D. Rimal, P. Stoler, M. Taiuti, E. L. Isupov, W. Tang, J. Bono, P. Nadel-Turonski, Ye Tian, Michael L. Williams, K. P. Adhikari, B. Dey, M. Osipenko, Diane Schott, G. Rosner, R. Nasseripour, A. I. Ostrovidov, K. Park, S. Boiarinov, K. Hicks, I. Bedlinskiy, D. G. Ireland, D. Martinez, Volker D. Burkert, A. S. Biselli, M. Mirazita, Barry Ritchie, F. X. Girod, A. Celentano, R. W. Gothe, Sergey Kuleshov, J. T. Goetz, V. Mokeev, W. Gohn, N. Gevorgyan, V. Batourine, C. Djalali, J. W. Price, S. Koirala, R. Paremuzyan, Lorenzo Zana, E. Phelps, S. Pisano, H. S. Jo, Gerard Gilfoyle, C. Salgado, D. Sokhan, Hovanes Egiyan, C. Munoz Camacho, R. P. Bennett, P. Collins, N. A. Baltzell, K. A. Griffioen, S. Taylor, Avraham Klein, M. Ungaro, M. Ripani, Michael Dugger, K. Joo, M. Bellis, R. Dupre, M. Battaglieri, S. Procureur, George Davey Smith, A. D'Angelo, L. El Fassi, M. E. McCracken, K. Livingston, and N. Dashyan
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, Current (mathematics), 010308 nuclear & particles physics, Theoretical models, Hyperon, Sigma, Lambda, 01 natural sciences, Nuclear physics, Isospin, 0103 physical sciences, Effective lagrangian, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, Differential (mathematics)
Abstract: We report the exclusive photoproduction cross sections for the Sigma(1385), Lambda(1405), and Lambda(1520) in the reactions gamma + p -> K+ + Y* using the CLAS detector for energies from near the respective production thresholds up to a center-of-mass energy W of 2.85 GeV. The differential cross sections are integrated to give the total exclusive cross sections for each hyperon. Comparisons are made to current theoretical models based on the effective Lagrangian approach and fitted to previous data. The accuracy of these models is seen to vary widely. The cross sections for the Lambda(1405) region are strikingly different for the Sigma+pi-, Sigma0 pi0, and Sigma- pi+ decay channels, indicating the effect of isospin interference, especially at W values close to the threshold.
Published: 2013

41. Demonstration of a novel technique to measure two-photon exchange effects in elastice±pscattering

Author: R. P. Bennett, P. Eugenio, J. Bono, N. A. Baltzell, K. A. Griffioen, Andrew Puckett, S. Strauch, Martin K. Mayer, H. Y. Lu, M. MacCormick, A. Deur, R. Paremuzyan, M. Battaglieri, M. S. Saini, I. Zonta, H. Egiyan, Gerard Gilfoyle, R. De Vita, D. Sokhan, I. Niculescu, J. T. Goetz, B. McKinnon, P. Collins, S. Tkachenko, E. Seder, M. Mirazita, E. Phelps, S. Anefalos Pereira, L. Guo, Z. W. Zhao, G. Rosner, R. Nasseripour, N. Gevorgyan, S. Chandavar, W. Gohn, D. Ho, V. Batourine, Kei Moriya, C. E. Taylor, William Brooks, S. E. Kuhn, O. Cortes, V. P. Kubarovsky, G. V. Fedotov, E. L. Isupov, Ye Tian, J. A. Fleming, S. Park, J. Zhang, Andrei Afanasev, E. De Sanctis, E. Golovatch, O. Pogorelko, S. Boiarinov, A. Celentano, R. Dupre, R. W. Gothe, P. Rossi, M. Aghasyan, R. A. Schumacher, C. Munoz Camacho, K. P. Adhikari, Lorenzo Zana, H. Avakian, J. Lachniet, D. I. Sober, H. Hakobyan, C. Hanretty, S. Procureur, N. Harrison, Maryam Moteabbed, E. Munevar, B. S. Ishkhanov, V. Crede, C. Salgado, N. K. Walford, M. Ungaro, H. Voskanyan, R. A. Montgomery, Chaden Djalali, Elton Smith, M. R. Niroula, H. Seraydaryan, Y. G. Sharabian, A. Kubarovsky, S. Lewis, F. Sabatié, S. Stepanyan, G. Niculescu, W. J. Briscoe, I. Bedlinskiy, H. S. Jo, K. Joo, T. Mineeva, J. J. Phillips, George Davey Smith, Dustin Keller, S. Fegan, S. Pisano, I. J. D. MacGregor, S. Koirala, A. Kim, W. Tang, Michael Wood, M. Contalbrigo, A. D'Angelo, M. Osipenko, K. Hafidi, Victor Mokeev, K. Hicks, D. Martinez, F. X. Girod, N. Dashyan, L. El Fassi, J. W. Price, D. Protopopescu, P. Nadel-Turonski, S. Pozdniakov, E. Voutier, Diane Schott, A. I. Ostrovidov, K. Park, D. G. Ireland, N. Guler, Volker D. Burkert, A. S. Biselli, Y. Ilieva, Nicholas Zachariou, J. P. Ball, D. Rimal, R. G. Fersch, D. S. Carman, P. L. Cole, D. Doughty, S. Niccolai, D. Heddle, M. J. Amaryan, H. Moutarde, K. L. Giovanetti, Sergey Kuleshov, D. Adikaram, Larry Weinstein, M. Guidal, M. Holtrop, Luciano Pappalardo, M. Khandaker, C. E. Hyde, Friedrich Klein, J. Arrington, Brian Raue, and M. Ripani
Subjects: Elastic scattering, Physics, Nuclear and High Energy Physics, Photon, Proton, 010308 nuclear & particles physics, Scattering, Electron, 01 natural sciences, Nuclear physics, Positron, 0103 physical sciences, Physics::Accelerator Physics, High Energy Physics::Experiment, Atomic physics, 010306 general physics, Electron scattering, Beam (structure)
Abstract: Background: The discrepancy between proton electromagnetic form factors extracted using unpolarized and polarized scattering data is believed to be a consequence of two-photon exchange (TPE) effects. However, the calculations of TPE corrections have significant model dependence, and there is limited direct experimental evidence for such corrections. Purpose: The TPE contributions depend on the sign of the lepton charge in e(+/-)p scattering, but the luminosities of secondary positron beams limited past measurement at large scattering angles, where the TPE effects are believe to be most significant. We present the results of a new experimental technique for making direct e(+/-)p comparisons, which has the potential to make precise measurements over a broad range in Q(2) and scattering angles. Methods: We use the Jefferson Laboratory electron beam and the Hall B photon tagger to generate a clean but untagged photon beam. The photon beam impinges on a converter foil to generate a mixed beam of electrons, positrons, and photons. A chicane is used to separate and recombine the electron and positron beams while the photon beam is stopped by a photon blocker. This provides a combined electron and positron beam, with energies from 0.5 to 3.2 GeV, which impinges on a liquid hydrogen target. The large acceptance CLAS detector is used to identify and reconstruct elastic scattering events, determining both the initial lepton energy and the sign of the scattered lepton. Results: The data were collected in two days with a primary electron beam energy of only 3.3 GeV, limiting the data from this run to smaller values of Q(2) and scattering angle. Nonetheless, this measurement yields a data sample for e(+/-)p with statistics comparable to those of the best previous measurements. We have shown that we can cleanly identify elastic scattering events and correct for the difference in acceptance for electron and positron scattering. Because we ran with only one polarity for the chicane, we are unable to study the difference between the incoming electron and positron beams. This systematic effect leads to the largest uncertainty in the final ratio of positron to electron scattering: R = 1.027 +/- 0.005 +/- 0.05 for = 0.206 GeV2 and 0.830
Published: 2013

42. Cross sections for theγp→K+Λandγp→K+Σ0reactions measured at CLAS

Author: N. K. Walford, H. Voskanyan, W. J. Briscoe, E. Pasyuk, V. Mokeev, P. Khetarpal, Michael Wood, K. Hafidi, A. V. Vlassov, Diane Schott, I. I. Strakovsky, V. P. Kubarovsky, O. Pogorelko, P. Eugenio, R. Dupre, Y. Prok, M. Battaglieri, D. S. Carman, A. I. Ostrovidov, R. De Vita, K. Park, A. Deur, C. A. Meyer, F. X. Girod, G. V. Fedotov, I. Zonta, D. G. Ireland, E. Voutier, S. Strauch, D. P. Watts, P. Collins, C. Munoz Camacho, Volker D. Burkert, A. S. Biselli, R. Paremuzyan, W. Kim, G. Niculescu, M. Ungaro, R. A. Schumacher, S. H. Kim, S. Anefalos Pereira, S. Fegan, Friedrich Klein, B. Vernarsky, C. S. Nepali, George Davey Smith, K. P. Adhikari, Gerard Gilfoyle, P. Stoler, D. P. Weygand, D. Sokhan, Z. W. Zhao, E. De Sanctis, D. Ho, W. Tang, K. Joo, Brian Raue, J. W. Price, G. Rosner, M. Aghasyan, Hyun-Chul Kim, M. Osipenko, D. I. Sober, A. D'Angelo, B. McKinnon, S. Stepanyan, W. Gohn, J. J. Phillips, C. E. Hyde, F. Sabatié, D. Martinez, N. Markov, M. Y. Gabrielyan, E. Munevar, S. Koirala, N. Dashyan, I. J. D. MacGregor, K. Hicks, C. E. Taylor, S. Pisano, L. El Fassi, H. Y. Lu, M. Contalbrigo, S. Niccolai, N. A. Baltzell, J. Bono, P. Nadel-Turonski, E. Golovatch, S. Tkachenko, Barry Ritchie, A. Kim, N. Gevorgyan, David M. Keller, K. A. Griffioen, E. Phelps, G. Charles, S. Chandavar, L. Guo, Y. Mao, H. Hakobyan, C. Hanretty, D. Protopopescu, I. Niculescu, B. S. Ishkhanov, P. L. Cole, A. Celentano, R. W. Gothe, I. Bedlinskiy, S. Pozdniakov, N. Harrison, S. Procureur, C. Djalali, M. Khandaker, A. El Alaoui, Y. Ilieva, Nicholas Zachariou, M. J. Amaryan, H. Moutarde, D. Rimal, K. L. Giovanetti, Larry Weinstein, D. Doughty, K. Livingston, D. Heddle, Jie Zhang, B. Torayev, M. Guidal, M. Holtrop, S. Park, P. Rossi, Luciano Pappalardo, V. Crede, M. Ripani, S. S. Stepanyan, A. Kubarovsky, Andrew Puckett, Sergey Kuleshov, Martin K. Mayer, M. S. Saini, J. A. Fleming, H. Seraydaryan, Y. G. Sharabian, Lorenzo Zana, H. S. Jo, C. Salgado, O. Cortes, E. L. Isupov, Ye Tian, and S. Boiarinov
Subjects: Physics, Nuclear and High Energy Physics, Meson production, Photon, 010308 nuclear & particles physics, Hyperon, 7. Clean energy, 01 natural sciences, Nuclear physics, Cross section (physics), 0103 physical sciences, Isobar, Atomic physics, 010306 general physics, Legendre polynomials
Abstract: The first high-statistics cross sections for the reactions γp→K*+Λ and γp→K*+Σ0 were measured using the CLAS detector at photon energies between threshold and 3.9 GeV at the Thomas Jefferson National Accelerator Facility. Differential cross sections are presented over the full range of the center-of-mass angles, and then fitted to Legendre polynomials to extract the total cross section. Results for the K*+Λ final state are compared with two different calculations in an isobar and a Regge model, respectively. Theoretical calculations significantly underestimate the K*+Λ total cross sections between 2.1 and 2.6 GeV, but are in better agreement with present data at higher photon energies.
Published: 2013

43. Transverse polarization ofΣ+(1189)in photoproduction on a hydrogen target in CLAS

Author: M. Taiuti, B. S. Ishkhanov, H. Hakobyan, C. Hanretty, V. Mokeev, A. Kim, K. Hafidi, Z. W. Zhao, P. Khetarpal, M. Khandaker, I. Bedlinskiy, D. Ho, G. Charles, E. De Sanctis, F. X. Girod, S. E. Kuhn, Friedrich Klein, M. Aghasyan, Brian Raue, D. I. Sober, D. Protopopescu, V. Crede, R. A. Schumacher, Barry Ritchie, S. S. Stepanyan, B. Vernarsky, J. A. Fleming, S. Pozdniakov, F. Sabatié, D. Doughty, I. Zonta, J. W. Price, A. V. Vlassov, G. Rosner, N. K. Walford, H. Voskanyan, W. J. Briscoe, D. I. Glazier, George Davey Smith, E. Pasyuk, S. Fegan, C. E. Hyde, D. Heddle, R. A. Montgomery, S. Koirala, R. De Vita, S. Bültmann, W. Tang, M. Osipenko, David M. Keller, S. Anefalos Pereira, K. Hicks, S. Stepanyan, E. Munevar, B. Torayev, S. Tkachenko, T. Mineeva, E. Phelps, Avraham Klein, L. El Fassi, C. E. Taylor, S. Niccolai, Jie Zhang, M. J. Amaryan, E. Golovatch, W. Kim, N. Dashyan, N. Harrison, H. Seraydaryan, G. Niculescu, N. Guler, E. Seder, S. Park, R. W. Gothe, V. P. Kubarovsky, R. G. Fersch, P. Rossi, I. I. Strakovsky, H. Y. Lu, Y. G. Sharabian, P. L. Cole, O. Pogorelko, A. Deur, H. Baghdasaryan, C. S. Nepali, G. V. Fedotov, I. Niculescu, A. El Alaoui, Y. Ilieva, K. L. Giovanetti, Andrew Puckett, Martin K. Mayer, Nicholas Zachariou, K. P. Adhikari, D. P. Weygand, N. D. Kvaltine, C. Munoz Camacho, Larry Weinstein, M. S. Saini, J. P. Ball, D. Rimal, M. Ripani, D. S. Carman, J. J. Phillips, N. Markov, I. J. D. MacGregor, W. Gohn, B. McKinnon, M. Contalbrigo, S. Pisano, Sergey Kuleshov, M. Guidal, M. Mirazita, M. Holtrop, N. Gevorgyan, V. Batourine, Luciano Pappalardo, Diane Schott, A. I. Ostrovidov, K. Park, R. Paremuzyan, D. G. Ireland, Volker D. Burkert, A. S. Biselli, D. Sokhan, Lorenzo Zana, H. S. Jo, Andrea Celentano, S. Procureur, C. Salgado, S. Strauch, D. P. Watts, M. Y. Gabrielyan, E. L. Isupov, Ye Tian, S. Chandavar, C. Djalali, K. A. Griffioen, S. Boiarinov, R. Dupre, E. Voutier, M. Battaglieri, J. T. Goetz, P. Collins, J. Bono, and P. Nadel-Turonski
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, Meson, 010308 nuclear & particles physics, Quark model, Hyperon, Photon energy, Lambda, 01 natural sciences, Baryon, Nuclear physics, Pion, 0103 physical sciences, High Energy Physics::Experiment, Invariant mass, Nuclear Experiment, 010306 general physics
Abstract: Experimental results on the $$\Sigma^+(1189)$$ hyperon transverse polarization in photoproduction on a hydrogen target using the CLAS detector at Jefferson laboratory are presented. The $$\Sigma^+(1189)$$ was reconstructed in the exclusive reaction $$\gamma+p\rightarrow K^{0}_{S} + \Sigma^+(1189)$$ via the $$\Sigma^{+} \to p \pi^{0}$$ decay mode. The $$K^{0}_S$$ was reconstructed in the invariant mass of two oppositely charged pions with the $$\pi^0$$ identified in the missing mass of the detected $$p\pi^+\pi^-$$ final state. Experimental data were collected in the photon energy range $$E_{\gamma}$$ = 1.0-3.5 GeV ($$\sqrt{s}$$ range 1.66-2.73 GeV). We observe a large negative polarization of up to 95%. As the mechanism of transverse polarization of hyperons produced in unpolarized photoproduction experiments is still not well understood, these results will help to distinguish between different theoretical models on hyperon production and provide valuable information for the searches of missing baryon resonances.
Published: 2013

44. Measurement of theΣπphotoproduction line shapes near theΛ(1405)

Author: P. Eugenio, B. S. Ishkhanov, R. A. Schumacher, P. Collins, C. E. Taylor, F. X. Girod, C. E. Hyde, H. Hakobyan, W. Tang, M. D. Mestayer, E. Golovatch, P. Khetarpal, N. A. Baltzell, K. A. Griffioen, J. P. Ball, D. S. Carman, C. Hanretty, M. Osipenko, E. L. Isupov, D. Adikaram, M. Guidal, Barry Ritchie, R. Paremuzyan, S. Taylor, Diane Schott, Ye Tian, Michael L. Williams, P. L. Cole, A. I. Ostrovidov, K. Park, M. Holtrop, S. Stepanyan, E. Munevar, Gerard Gilfoyle, D. Protopopescu, J. W. Price, S. Pozdniakov, Avraham Klein, D. G. Ireland, Z. W. Zhao, G. Charles, M. E. McCracken, S. Tkachenko, D. Ho, B. Vernarsky, Volker D. Burkert, A. S. Biselli, I. Bedlinskiy, A. Kim, R. Dupre, N. K. Walford, M. Battaglieri, S. Strauch, S. S. Stepanyan, S. Koirala, H. Voskanyan, D. P. Watts, L. L. Pappalardo, I. Zonta, A. Celentano, R. W. Gothe, W. J. Briscoe, E. Pasyuk, N. Harrison, George Davey Smith, N. D. Kvaltine, A. Kubarovsky, K. Livingston, V. Mokeev, J. Bono, P. Nadel-Turonski, H. Y. Lu, S. Park, Jie Zhang, A. D'Angelo, W. Gohn, S. Niccolai, Sergey Kuleshov, Friedrich Klein, R. Fersch, E. Seder, S. Chandavar, T. Mineeva, Hovanes Egiyan, P. Rossi, C. Munoz Camacho, I. Niculescu, L. El Fassi, S. Fegan, N. Pivnyuk, R. Nasseripour, P. Stoler, I. I. Strakovsky, V. P. Kubarovsky, Kei Moriya, B. Dey, C. A. Meyer, F. Sabatié, O. Pogorelko, K. Hicks, W. Kim, G. V. Fedotov, V. Crede, C. Djalali, B. McKinnon, Y. Ilieva, G. Niculescu, S. Procureur, Nicholas Zachariou, A. Deur, R. A. Montgomery, G. Rosner, M. Taiuti, Dustin Keller, E. Voutier, N. Markov, D. Rimal, K. P. Adhikari, D. P. Weygand, S. Pisano, C. S. Nepali, K. Hafidi, M. Mirazita, N. Dashyan, E. Phelps, N. Gevorgyan, V. Batourine, M. Bellis, J. J. Phillips, I. J. D. MacGregor, Elton Smith, M. Ripani, H. Seraydaryan, Y. G. Sharabian, Martin K. Mayer, M. S. Saini, M. Khandaker, D. Doughty, J. A. Fleming, D. Heddle, B. Torayev, A. V. Vlassov, K. L. Giovanetti, R. De Vita, S. Anefalos Pereira, E. De Sanctis, M. Aghasyan, D. I. Sober, M. Ungaro, S. Boiarinov, J. T. Goetz, Lorenzo Zana, H. S. Jo, and C. Salgado
Subjects: Physics, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Quark model, Sigma, Lambda, 01 natural sciences, Baryon, Amplitude, Isospin, 0103 physical sciences, Invariant mass, Production (computer science), Atomic physics, 010306 general physics
Abstract: The reaction {gamma} + p -> K{sup +} + {Sigma} + {p}i was used to determine the invariant mass distributions or "line shapes" of the {Sigma}{sup +} {pi}{sup -}, {Sigma}{sup -} {pi}{sup +} and {Sigma}{sup 0} {pi}{sup 0} final states, from threshold at 1328 MeV/c^2 through the mass range of the {Lambda}(1405) and the {Lambda}(1520). The measurements were made with the CLAS system at Jefferson Lab using tagged real photons, for center-of-mass energies 1.95 < W < 2.85 GeV. The three mass distributions differ strongly in the vicinity of the I=0 {Lambda}(1405), indicating the presence of substantial I=1 strength in the reaction. Background contributions to the data from the {Sigma}{sup 0}(1385) and from K* {Sigma} production were studied and shown to have negligible influence. To separate the isospin amplitudes, Breit-Wigner model fits were made that included channel-coupling distortions due to the Nkbar threshold. A best fit to all the data was obtained after including a phenomenological I=1, J{sup P} = 1/2{sup -} amplitude with a centroid at 1394\pm20 MeV/c^2 and a second I=1 amplitude at 1413\pm10 MeV/c^2. The centroid of the I=0 {Lambda}(1405) strength was found at the {Sigma} {pi} threshold, with the observed shape determined largely by channel-coupling, leadingmore » to an apparent overall peak near 1405 MeV/c^2.« less
Published: 2013

45. Separated structure functions for exclusiveK+ΛandK+Σ0electroproduction at 5.5 GeV measured with CLAS

Author: N. A. Baltzell, E. De Sanctis, M. Aghasyan, H. Y. Lu, M. D. Mestayer, S. Strauch, G. Charles, D. I. Sober, O. Cortes, E. L. Isupov, Ye Tian, S. Procureur, Y. Prok, M. Ungaro, Eugene Pasyuk, D. P. Watts, P. Stoler, F. X. Girod, S. Boiarinov, M. Anghinolfi, H. Seraydaryan, M. Contalbrigo, V. P. Kubarovsky, D. Doughty, C. Hanretty, A. Fradi, Y. G. Sharabian, M. Ripani, I. Niculescu, R. De Vita, A. El Alaoui, V. Mokeev, O. Pogorelko, K. Joo, J. T. Goetz, K. Hicks, D. Heddle, J. W. Price, S. Anefalos Pereira, M. Y. Gabrielyan, Andrew Puckett, Martin K. Mayer, Dustin Keller, C. Munoz Camacho, J. P. Ball, S. Lewis, R. A. Schumacher, D. S. Carman, S. Pisano, B. McKinnon, M. S. Saini, S. Koirala, Sergey Kuleshov, R. Dupre, Nicholas Zachariou, D. Rimal, P. L. Cole, C. Djalali, Michael Wood, I. Bedlinskiy, S. Chandavar, M. Mirazita, E. Phelps, K. Hafidi, S. Park, M. Battaglieri, N. Gevorgyan, George Davey Smith, S. Tkachenko, V. Batourine, E. Voutier, E. Seder, L. Guo, Lorenzo Zana, I. Zonta, Diane Schott, H. Avakian, A. I. Ostrovidov, K. Park, R. Nasseripour, K. Livingston, J. A. Fleming, W. Kim, N. K. Walford, T. Mineeva, N. Harrison, A. D'Angelo, S. Stepanyan, H. Hakobyan, H. S. Jo, E. Munevar, C. A. Meyer, H. Voskanyan, R. Paremuzyan, G. V. Fedotov, I. I. Strakovsky, B. Guegan, Avraham Klein, K. A. Griffioen, D. G. Ireland, Y. Ilieva, Jie Zhang, G. Niculescu, S. Fegan, W. J. Briscoe, J. Bono, P. Nadel-Turonski, V. Crede, C. Salgado, P. Eugenio, J. J. Phillips, L. El Fassi, A. Deur, M. Taiuti, K. P. Adhikari, D. Sokhan, S. Niccolai, William Brooks, Volker D. Burkert, A. S. Biselli, R. Fersch, Y. Mao, S. S. Stepanyan, P. Khetarpal, I. J. D. MacGregor, N. Dashyan, C. S. Nepali, C. E. Taylor, R. A. Montgomery, N. A. Saylor, A. Trivedi, N. D. Kvaltine, H. Baghdasaryan, W. Tang, P. Rossi, A. Celentano, R. W. Gothe, Z. W. Zhao, A. Kubarovsky, M. Osipenko, B. Vernarsky, D. Ho, D. Adikaram, M. Khandaker, M. Guidal, B. S. Ishkhanov, D. Protopopescu, D. Martinez, S. Pozdniakov, W. Gohn, M. Holtrop, Luciano Pappalardo, M. J. Amaryan, H. Moutarde, K. L. Giovanetti, G. Rosner, Larry Weinstein, F. Sabatié, G. Ricco, Friedrich Klein, Brian Raue, and A. Kim
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, Meson, 010308 nuclear & particles physics, Structure function, Hyperon, Sigma, Polarization (waves), Lambda, 01 natural sciences, Baryon, Nuclear physics, Pion, 0103 physical sciences, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics
Abstract: We report measurements of the exclusive electroproduction of K{sup +}{Lambda} and K{sup +}{Sigma}{sup 0} final states from an unpolarized proton target using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The separated structure functions {sigma}{sub U}, {sigma}{sub LT}, {sigma}{sub TT}, and {sigma}{sub LT'} were extracted from the {Phi}-dependent differential cross sections acquired with a longitudinally polarized 5.499~GeV electron beam. The data span a broad range of momentum transfers Q{sup 2} from 1.4 to 3.9 GeV{sup 2}, invariant energy W from threshold to 2.6 GeV, and nearly the full center-of-mass angular range of the kaon. The separated structure functions provide an unprecedented data sample, which in conjunction with other meson photo- and electroproduction data, will help to constrain the higher-level analyses being performed to search for missing baryon resonances.
Published: 2013

46. Comment on 'Observation of a narrow structure in1H(γ,KS0)Xvia interference withϕ-meson production'

Author: A. Celentano, B. McKinnon, M. Ungaro, B. Zhao, G. Ricco, D. Doughty, A. I. Ostrovidov, K. Park, A. El Alaoui, P. Stoler, Nicholas Zachariou, D. Heddle, B. Dey, Volker D. Burkert, Sergey Kuleshov, R. De Vita, K. Hicks, M. Mirazita, F. X. Girod, R. A. Schumacher, M. Guidal, S. Anefalos Pereira, Michael Dugger, J. T. Goetz, S. Park, R. Dickson, S. Niccolai, S. S. Stepanyan, E. Seder, A. Ni, M. Holtrop, Elton Smith, J. W. Price, M. Bellis, L. Guo, E. De Sanctis, M. Anghinolfi, H. Y. Lu, D. G. Ireland, V. Crede, D. I. Sober, Y. G. Sharabian, N. A. Baltzell, Gerard Gilfoyle, I. Niculescu, P. L. Cole, R. Dupre, D. Schott, Paolo Rossi, M. Battaglieri, M. E. McCracken, P. Eugenio, J. P. Ball, I. Bedlinskiy, D. S. Carman, Michael Wood, K. Hafidi, S. Pozdniakov, M. Garçon, B. Morrison, K. L. Giovanetti, M. Ripani, B. S. Ishkhanov, Barry Ritchie, L. El Fassi, P. Khetarpal, Latifa Elouadrhiri, Kei Moriya, C. A. Meyer, B. Vernarsky, G. V. Fedotov, V. P. Kubarovsky, D. P. Weygand, O. Pogorelko, A. S. Biselli, P. Bosted, C. Bookwalter, N. Markov, S. Pisano, A. Kim, E. Golovatch, W. Tang, Michael Vineyard, M. Osipenko, H. Hakobyan, I. J. D. MacGregor, H. S. Jo, W. Kim, G. Niculescu, H. Egiyan, M. Y. Gabrielyan, M. D. Mestayer, V. Mokeev, E. L. Isupov, S. Chandavar, and S. Boiarinov
Subjects: Nuclear physics, Physics, Nuclear and High Energy Physics, Meson production, Meson, Structure (category theory), Mass spectrum, Interference (wave propagation), Pentaquark, Interpretation (model theory)
Abstract: In Ref. [1], the authors claim to observe a narrow structure in the mass spectrum constructed from the (pK_L) system using data from the CLAS detector. The interpretation of this narrow structure given in Ref. [1] is as follows: “It may be due to the photoproduction of the Theta+ pentaquark or some unknown Sigma∗ resonance.” The authors go on to say that “it is unlikely for the observed structure to be due to a Sigma∗ resonance.” This analysis was reviewed by the CLAS Collaboration, following the established procedures for all CLAS papers, and did not receive approval. The purpose of this Comment is to explain the reasons why that analysis was not approved for publication.
Published: 2012

47. Experimental study of theP11(1440)andD13(1520)resonances from the CLAS data onep→e′π+π−p′

Author: M. Contalbrigo, I. Zonta, W. Kim, Friedrich Klein, I. I. Strakovsky, M. Guidal, S. Tkachenko, Brian Raue, P. Khetarpal, L. Guo, A. Deur, M. Holtrop, W. K. Brooks, C. S. Nepali, A. Daniel, A. Kim, N. A. Baltzell, H. Moutarde, Luciano Pappalardo, P. Eugenio, C. E. Taylor, J. Ball, V. P. Kubarovsky, A. Celentano, R. W. Gothe, S. S. Stepanyan, A. El Alaoui, Y. Ilieva, V. Crede, O. Pogorelko, E. Golovatch, P. Stoler, H. Hakobyan, L. C. Smith, Nicholas Zachariou, S. Strauch, C. Hanretty, D. Sokhan, M. Anghinolfi, K. Hicks, B. S. Ishkhanov, S. Koirala, H. Seraydaryan, A. Kubarovsky, D. Rimal, W. Tang, Y. G. Sharabian, S. Procureur, K. L. Giovanetti, Z. W. Zhao, A Fradi, H. Y. Lu, I. Bedlinskiy, Michael Wood, E. Seder, H. S. Jo, K. Hafidi, B. Guegan, D. Ho, M. Ungaro, E. De Sanctis, Martin K. Mayer, M. Ripani, K. A. Griffioen, Latifa Elouadrhiri, M. Aghasyan, G. Charles, D. Martinez, Sergey Kuleshov, H. Avakian, D. I. Sober, R. Paremuzyan, C. A. Meyer, Y. Mao, M. S. Saini, G. V. Fedotov, A. Trivedi, I. J. D. MacGregor, B. McKinnon, S. Park, R. A. Schumacher, N. K. Walford, H. Voskanyan, W. J. Briscoe, N. Markov, M. Khandaker, K. P. Adhikari, S. Pisano, K. Livingston, P. Rossi, E. Pasyuk, L. Graham, M. Mirazita, R. Dupre, David M. Keller, M. Battaglieri, T. Mineeva, V. Batourine, A. I. Ostrovidov, R. De Vita, F. X. Girod, K. Park, D. Doughty, S. Stepanyan, D. G. Ireland, E. Munevar, K. Joo, Avraham Klein, E. L. Isupov, D. Protopopescu, P. L. Cole, S. Pozdniakov, Volker D. Burkert, A. S. Biselli, Ye Tian, F. Sabatié, W. Gohn, S. Anefalos Pereira, J. W. Price, D. Schott, S. Boiarinov, George Davey Smith, Michael Vineyard, A. D'Angelo, P. Nadel-Turonski, C. Salgado, Victor Mokeev, C. Djalali, N. D. Kvaltine, D. S. Carman, E. Voutier, G. Ricco, G. Rosner, S. Fegan, C. Bookwalter, N. Dashyan, and H. Baghdasaryan
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, Unitarity, Proton, 010308 nuclear & particles physics, Branching fraction, Hadron, 01 natural sciences, Helicity, Excited state, 0103 physical sciences, 010306 general physics, Ground state, Ansatz
Abstract: The transition helicity amplitudes from the proton ground state to the $$P_{11}(1440)$$ and $$D_{13}(1520)$$ excited states ($$\gamma_{v}pN^*$$ electrocouplings) were determined from the analysis of nine independent one-fold differential $$\pi^{+} \pi^{-} p$$ electroproduction cross sections off a proton target, taken with CLAS at photon virtualities 0.25\enskip {\rm GeV$$^{2}$$} $
Published: 2012

48. Measurement of Exclusiveπ0Electroproduction Structure Functions and their Relationship to Transverse Generalized Parton Distributions

Author: A. Kim, R. A. Schumacher, D. Doughty, D. Heddle, L. Graham, F. X. Girod, V. Mokeev, K. A. Griffioen, Y. Mao, S. Strauch, T. A. Forest, P. Nadel-Turonski, D. P. Watts, H. Egiyan, R. P. Bennett, S. Stepanyan, E. Munevar, M. Ungaro, A. V. Vlassov, I. Zonta, Eugene Pasyuk, A. I. Ostrovidov, K. Park, S. Tkachenko, D. G. Ireland, L. Guo, A. El Alaoui, Y. Ilieva, Volker D. Burkert, C. Munoz Camacho, Andrew Puckett, Martin K. Mayer, Nicholas Zachariou, A. S. Biselli, R. De Vita, W. Gohn, K. Joo, M. Khandaker, M. S. Saini, G. Ricco, C. E. Taylor, B. McKinnon, D. Rimal, W. Tang, E. Seder, I. J. D. MacGregor, M. Osipenko, S. Procureur, G. Charles, S. Anefalos Pereira, M. J. Amaryan, M. Mirazita, N. Markov, V. Crede, Latifa Elouadrhiri, S. Pisano, K. Livingston, N. Gevorgyan, N. A. Saylor, S. E. Kuhn, D. Martinez, B. Guegan, C. A. Meyer, A. Celentano, R. W. Gothe, J. A. Fleming, Friedrich Klein, G. V. Fedotov, H. Moutarde, M. Ripani, S. Fegan, Jie Zhang, Brian Raue, R. Paremuzyan, W. Kim, K. L. Giovanetti, G. Niculescu, F. Sabatié, N. D. Kvaltine, E. De Sanctis, H. Hakobyan, C. Djalali, R. Dupre, Larry Weinstein, M. Contalbrigo, M. Battaglieri, C. Hanretty, M. Aghasyan, A. Deur, K. P. Adhikari, D. I. Sober, M. Taiuti, David M. Keller, D. P. Weygand, W. K. Brooks, H. S. Jo, D. Sokhan, C. Bookwalter, P. Stoler, J. W. Price, Michael Wood, I. Bedlinskiy, K. Hafidi, K. Hicks, D. Protopopescu, S. Pozdniakov, M. Garçon, E. Voutier, S. Koirala, G. Rosner, S. Chandavar, E. Phelps, S. Park, N. Dashyan, P. Rossi, E. L. Isupov, V. P. Kubarovsky, A. Kubarovsky, Ye Tian, George Davey Smith, A. D'Angelo, O. Pogorelko, L. El Fassi, H. Avakian, H. Baghdasaryan, S. Boiarinov, M. Guidal, M. Holtrop, A. Daniel, Luciano Pappalardo, N. K. Walford, H. Voskanyan, W. J. Briscoe, J. P. Ball, Y. Prok, D. S. Carman, S. Niccolai, B. S. Ishkhanov, Sergey Kuleshov, H. Y. Lu, P. Khetarpal, N. A. Baltzell, A. Fradi, I. Niculescu, P. Eugenio, D. Schott, T. Mineeva, C. Salgado, Z. W. Zhao, M. F. Vineyard, M. Anghinolfi, H. Seraydaryan, and Y. G. Sharabian
Subjects: Physics, Particle physics, 010308 nuclear & particles physics, Structure function, General Physics and Astronomy, Sigma, Parton, 01 natural sciences, Helicity, Transverse plane, 0103 physical sciences, Sensitivity (control systems), 010306 general physics, Nucleon, Phenomenology (particle physics)
Abstract: Exclusive $$\pi^0$$ electroproduction at a beam energy of 5.75 GeV has been measured with the Jefferson Lab CLAS spectrometer. Differential cross sections were measured at more than 1800 kinematic values in $Q^2$, $x_B$, $t$, and $$\phi_\pi$$, in the $Q^2$ range from 1.0 to 4.6 GeV$^2$$,\ $$-t$ up to 2 GeV$^2$, and $x_B$ from 0.1 to 0.58. Structure functions $$\sigma_T +\epsilon \sigma_L, \sigma_{TT}$$ and $$\sigma_{LT}$$ were extracted as functions of $t$ for each of 17 combinations of $Q^2$ and $x_B$. The data were compared directly with two handbag-based calculations including both longitudinal and transversity GPDs. Inclusion of only longitudinal GPDs very strongly underestimates $$\sigma_T +\epsilon \sigma_L$$ and fails to account for $$\sigma_{TT}$$ and $$\sigma_{LT}$$, while inclusion of transversity GPDs brings the calculations into substantially better agreement with the data. There is very strong sensitivity to the relative contributions of nucleon helicity flip and helicity non-flip processes. The results confirm that exclusive $$\pi^0$$ electroproduction offers direct experimental access to the transversity GPDs.
Published: 2012

49. Measurement of the generalized form factors near threshold viaγ*p→nπ+at highQ2

Author: R. Paremuzyan, Gerard Gilfoyle, R. A. Schumacher, George Davey Smith, A. D'Angelo, R. Nasseripour, L. El Fassi, I. I. Strakovsky, A. Fradi, C. Bookwalter, K. A. Griffioen, L. Graham, W. Kim, Martin K. Mayer, C. E. Hyde, M. Contalbrigo, A. Deur, N. Kalantarians, D. Sokhan, V. P. Kubarovsky, H. Hakobyan, C. Hanretty, P. Eugenio, M. Taiuti, G. Niculescu, P. L. Cole, M. S. Saini, S. Pozdniakov, W. K. Brooks, E. Munevar, B. S. Ishkhanov, B. McKinnon, O. Pogorelko, N. Markov, S. Pisano, K. Livingston, D. Doughty, E. De Sanctis, J. P. Ball, I. Bedlinskiy, Y. Prok, J. T. Goetz, S. S. Stepanyan, S. Park, S. Stepanyan, D. Heddle, D. I. Sober, D. Branford, M. Mirazita, R. Dupre, M. Battaglieri, D. S. Carman, Avraham Klein, A. I. Ostrovidov, K. Park, A. Kubarovsky, P. Rossi, W. Tang, Z. W. Zhao, P. Stoler, D. G. Ireland, E. Phelps, N. Gevorgyan, W. Gohn, V. Batourine, H. S. Jo, W. J. Briscoe, C. E. Taylor, N. D. Kvaltine, S. Chandavar, V. Crede, F. Sabatié, H. Y. Lu, A. V. Vlassov, D. G. Jenkins, Volker D. Burkert, A. S. Biselli, M. Osipenko, C. Salgado, S. E. Kuhn, E. Golovatch, N. Dashyan, G. Ricco, Y. Ilieva, B. Zhao, A. Kim, C. A. Meyer, G. V. Fedotov, Sergey Kuleshov, F. X. Girod, T. Mineeva, K. Hicks, A. El Alaoui, R. De Vita, H. Baghdasaryan, D. Adikaram, M. Guidal, P. Khetarpal, I. Niculescu, M. Ripani, S. Strauch, Nicholas Zachariou, S. Niccolai, D. P. Watts, M. Holtrop, I. J. D. MacGregor, S. Anefalos Pereira, Friedrich Klein, A. Daniel, D. Schott, Michael Wood, K. Hafidi, J. W. Price, Elton Smith, Luciano Pappalardo, M. Khandaker, D. Rimal, A. Celentano, R. W. Gothe, M. Paolone, M. Y. Gabrielyan, B. Vernarsky, M. D. Mestayer, E. L. Isupov, S. Tkachenko, K. P. Adhikari, G. Charles, D. P. Weygand, Ye Tian, G. Rosner, S. Procureur, R. P. Bennett, L. Guo, S. Boiarinov, M. Anghinolfi, H. Moutarde, K. L. Giovanetti, H. Seraydaryan, Y. G. Sharabian, Barry Ritchie, C. Djalali, E. Voutier, P. Nadel-Turonski, M. Ungaro, K. Joo, Victor Mokeev, and A. Trivedi
Subjects: Physics, Nuclear and High Energy Physics, Proton, Spectrometer, 010308 nuclear & particles physics, Momentum transfer, Form factor (quantum field theory), 01 natural sciences, Transverse plane, Light cone, 0103 physical sciences, Cathode ray, Atomic physics, Nuclear Experiment, 010306 general physics, Multipole expansion
Abstract: We report the first extraction of the pion-nucleon multipoles near the production threshold for the nπ+ channel at relatively high momentum transfer (Q2 up to 4.2 GeV2). The dominance of the s-wave transverse multipole (E0+), expected in this region, allowed us to access the generalized form factor G1 within the light-cone sum-rule (LCSR) framework as well as the axial form factor GA. The data analyzed in this work were collected by the nearly 4π CEBAF Large Acceptance Spectrometer (CLAS) using a 5.754-GeV electron beam on a proton target. The differential cross section and the π-N multipole E0+/GD were measured using two different methods, the LCSR and a direct multipole fit. The results from the two methods are found to be consistent and almost Q2 independent.
Published: 2012

50. Electromagnetic decay of theΣ0(1385)toΛγ

Author: P. Nadel-Turonski, L. Casey, R. Dupre, R. Dickson, M. Battaglieri, J. P. Ball, D. S. Carman, E. De Sanctis, Y. G. Sharabian, V. Kuznetsov, M. Aghasyan, D. I. Sober, P. Eugenio, R. De Vita, A. M. Micherdzinska, S. Anefalos Pereira, G. Gavalian, M. Taiuti, E. Voutier, E. L. Isupov, D. Keller, H. Y. Lu, M. Ripani, S. Niccolai, M. Amarian, Kei Moriya, C. A. Meyer, G. V. Fedotov, M. Khandaker, B. Guegan, S. Fegan, I. Niculescu, D. Protopopescu, H. Hakobyan, Z. W. Zhao, George Davey Smith, K. P. Adhikari, D. G. Jenkins, S. Pozdniakov, A. D'Angelo, D. Doughty, M. S. Saini, D. Schott, R. P. Bennett, B. Morrison, R. A. Schumacher, R. Paremuzyan, L. El Fassi, S. Strauch, Michael Vineyard, Barry Ritchie, L. Graham, F. X. Girod, F. Sabatié, N. Dashyan, P. Konczykowski, D. P. Watts, C. Djalali, S. Procureur, I. Bedlinskiy, Elton Smith, N. Markov, Lorenzo Zana, P. L. Cole, A. Ni, A. El Alaoui, Y. Ilieva, S. Pisano, Sergey Kuleshov, T. A. Forest, Friedrich Klein, H. Seraydaryan, H. S. Jo, Brian Raue, A. Kim, Avraham Klein, Nicholas Zachariou, C. Salgado, H. Baghdasaryan, S. L. Careccia, M. Y. Gabrielyan, E. Seder, J. W. Price, S. Park, P. Khetarpal, K. L. Giovanetti, B. McKinnon, P. Rossi, Larry Weinstein, D. Adikaram, M. Guidal, D. Branford, V. Crede, M. Mirazita, M. Holtrop, B. Moreno, A. Daniel, N. Gevorgyan, C. Hanretty, G. Rosner, V. Batourine, Luciano Pappalardo, A. I. Ostrovidov, K. Park, D. G. Ireland, S. S. Stepanyan, Volker D. Burkert, A. S. Biselli, Victor Mokeev, Hovanes Egiyan, H. Moutarde, B. Vernarsky, K. Joo, E. Munevar, I. I. Strakovsky, A. Deur, W. K. Brooks, C. E. Taylor, E. Golovatch, W. Gohn, W. Kim, G. Niculescu, W. Tang, M. Osipenko, B. Zhao, S. S. Jawalkar, I. J. D. MacGregor, M. Contalbrigo, V. P. Kubarovsky, O. Pogorelko, R. W. Gothe, J. McAndrew, Michael Wood, K. Hafidi, W. J. Briscoe, E. Pasyuk, P. Stoler, B. Dey, and K. Hicks
Subjects: Physics, Nuclear and High Energy Physics, Meson, 010308 nuclear & particles physics, Hadron, Elementary particle, Lambda, Lambda baryon, 01 natural sciences, Sigma baryon, Nuclear physics, Particle decay, 0103 physical sciences, High Energy Physics::Experiment, Atomic physics, 010306 general physics, Nucleon
Abstract: The electromagnetic decay $\Sigma^0(1385) \to \Lambda \gamma$ was studied using the CLAS detector at the Thomas Jefferson National Accelerator Facility. A real photon beam with a maximum energy of 3.8 GeV was incident on a proton target, producing an exclusive final state of $K^+\Sigma^{*0}$. We report the decay widths ratio $\Sigma^0(1385) \to \Lambda\gamma$/ $\Sigma^0(1385) \to \Lambda\pi^0$ = $1.42 \pm 0.12(\text{stat})_{-0.07}^{+0.11}(\text{sys})$%. This ratio is larger than most theoretical predictions by factors ranging from 1.5-3, but is consistent with the only other experimental measurement. From the reported ratio we calculate the partial width and electromagnetic transition magnetic moment for $\Sigma^0(1385) \to \Lambda\gamma$.
Published: 2011

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