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1. Measurement of beam asymmetry for π−Δ++ photoproduction on the proton at Eγ=8.5GeV

Author

E. S. Smith, T. Erbora, Ilya Larin, V. V. Tarasov, J. Schwiening, K. Luckas, B. E. Cannon, A. Austregesilo, C. Fanelli, A. Hurley, H. Marukyan, J. Fitches, R.S. Pedroni, W. McGinley, C. A. Meyer, L. Guo, J. Reinhold, A. Ali, T. D. Beattie, S. Furletov, M. M. Dalton, A. Smith, Z. Zhao, M. M. Ito, G. Rodriguez, F. Barbosa, D. Romanov, W. J. Briscoe, V. A. Matveev, A. M. Schertz, D. G. Ireland, V. Crede, T. Daniels, L. Gan, H. Egiyan, B. C.L. Sumner, A. LaDuke, G. J. Lolos, C. S. Akondi, V. Lyubovitskij, S. Somov, S. Fegan, R. Barsotti, S. Adhikari, M. R. Shepherd, A. Gasparian, E. Pooser, T. Whitlatch, N. Wickramaarachchi, Xiang Zhou, T. Britton, Sergey Kuleshov, B. Liu, M. Khatchatryan, H. Hakobyan, A. I. Ostrovidov, D. I. Lersch, K. Suresh, H. Li, P. Eugenio, W. B. Li, J. Barlow, Stephen Taylor, W. Phelps, J. Ritman, J. R. Stevens, M. McCaughan, Haiyan Gao, Mark Richard James Williams, Michael Dugger, Q. Zhou, Barry Ritchie, G. M. Huber, D. I. Sober, C. Gleason, K. Livingston, A. Thiel, A. Hamdi, I. I. Strakovsky, A. Schick, E. Barriga, V. S. Goryachev, A. Deur, Carlos A. Salgado, P. Pauli, V. Neelamana, Z. Baldwin, Z. Papandreou, O. Soto, R. Dzhygadlo, S. Schadmand, I. Jaegle, V. Khachatryan, J. Zarling, R. Dotel, Krisztian Peters, K. Goetzen, M. J. Amaryan, A. Asaturyan, F. Nerling, R. A. Schumacher, X. Shen, Christine Kourkoumelis, R. E. Mitchell, R. A. Miskimen, B. Zihlmann, L. Ng, A. Ernst, Zhiyong Zhang, V. V. Berdnikov, G. Vasileiadis, W.U. Boeglin, V. Kakoyan, D. J. Mack, D. Lawrence, Sean A Dobbs, A. Somov, William Brooks, Lubomir Pentchev, C. Paudel, A. M. Foda, G. Kalicy, N. S. Jarvis, A. Dolgolenko, S. Cole, O. Cortes, C.P. Romero, T. C. Black, R. T. Jones, M. E. McCracken, J. Zhou, K. Mizutani, M. Kamel, A. Teymurazyan, Y. Yang, and E. Chudakov

Subjects
Physics, Range (particle radiation), GlueX, Proton, Meson, 010308 nuclear & particles physics, media_common.quotation_subject, Momentum transfer, 01 natural sciences, Asymmetry, Pseudoscalar, Nuclear physics, Pion, 0103 physical sciences, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, media_common
Abstract

We report a measurement of the π − photoproduction beam asymmetry for the reaction → γ p → π − Δ + + using data from the GlueX experiment in the photon beam energy range 8.2–8.8 GeV. The asymmetry Σ is measured as a function of four-momentum transfer t to the Δ + + and compared to phenomenological models. We find that Σ varies as a function of t : negative at smaller values and positive at higher values of | t | . The reaction can be described theoretically by t -channel particle exchange requiring pseudoscalar, vector, and tensor intermediaries. In particular, this reaction requires charge exchange, allowing us to probe pion exchange and the significance of higher-order corrections to one-pion exchange at low momentum transfer. Constraining production mechanisms of conventional mesons may aid in the search for and study of unconventional mesons. This is the first measurement of the process at this energy.

Published
2021

2. Measurement of the photon beam asymmetry in γ⃗p→K+Σ0 at Eγ=8.5 GeV

Author

T. D. Beattie, K. Goetzen, W. J. Briscoe, P. Pauli, G. M. Huber, D. I. Sober, M. J. Amaryan, V. Crede, M. M. Dalton, V. S. Goryachev, Christine Kourkoumelis, A. Hurley, R. E. Mitchell, G. Kalicy, N. S. Jarvis, C. A. Meyer, L. Ng, D. Lawrence, A. Ernst, H. Hakobyan, V. Lyubovitskij, G. J. Lolos, I. Larin, C. Salgado, R. Barsotti, S. Adhikari, O. Cortes, Sean A Dobbs, T. Britton, A. Somov, A. Ali, Sergey Kuleshov, C.P. Romero, P. Eugenio, R. A. Schumacher, D. I. Lersch, K. Livingston, M. M. Ito, Barry Ritchie, N. Cao, Ashot Gasparian, A. Hamdi, Krisztian Peters, Michael Dugger, T. C. Black, I. I. Strakovsky, J. Barlow, Joerg Reinhold, S. Fegan, A. Deur, S. Cole, J. Frye, E. Pooser, V. A. Matveev, N. Qin, J. Schwiening, O. Soto, A. M. Schertz, T. Whitlatch, L. Robison, T. Daniels, B. E. Cannon, T. Erbora, H. Ni, Z. Papandreou, Ting Xiao, V. V. Berdnikov, William Brooks, J. R. Stevens, M. McCaughan, Mark Richard James Williams, Lubomir Pentchev, C. Gleason, S. Furletov, Q. Zhou, A. M. Foda, Dmitri Romanov, H. Marukyan, R.S. Pedroni, W. U. Boeglin, W. McGinley, E. Chudakov, N. Wickramaarachchi, A. Thiel, K. K. Seth, C. Fanelli, M. Kamel, W. Phelps, F. Nerling, Elton Smith, B. Liu, G. Vasileiadis, A. Austregesilo, Zhiyong Zhang, M. R. Shepherd, A. Teymurazyan, R. T. Jones, Y. Yang, M. E. McCracken, Xiang Zhou, S. Taylor, L. Gan, S. Somov, L. Guo, J. Zarling, C. Paudel, A. Dolgolenko, V. V. Tarasov, E. Barriga, M. Patsyuk, J. Foote, X. Shen, K. Suresh, Hovanes Egiyan, R. A. Miskimen, R. Dzhygadlo, F. Barbosa, V. Kakoyan, D. J. Mack, A. Goncalves, R. Dotel, B. Zihlmann, A. I. Ostrovidov, H. Li, D. G. Ireland, and W. B. Li

Subjects
Physics, Range (particle radiation), GlueX, Spectrometer, 010308 nuclear & particles physics, Linear polarization, media_common.quotation_subject, Theoretical models, 01 natural sciences, Asymmetry, Nuclear physics, 0103 physical sciences, High Energy Physics::Experiment, Photon beam, Nuclear Experiment, 010306 general physics, Beam (structure), media_common
Abstract

We report measurements of the photon beam asymmetry Σ for the reaction γp→K+Σ0 (1193) using the GlueX spectrometer in Hall D at Jefferson Lab. Data were collected by using a linearly polarized photon beam in the energy range of 8.2–8.8 GeV incident on a liquid hydrogen target. The beam asymmetry Σ was measured as a function of the Mandelstam variable t , and a single value of Σ was extracted for events produced in the u channel. These are the first exclusive measurements of the photon beam asymmetry Σ for the reaction in this energy range. For the t channel, the measured beam asymmetry is close to unity over the t range studied, − t = ( 0.1 – 1.4 ) ( GeV / c ) 2 , with an average value of Σ = 1.00 ± 0.05 . This agrees with theoretical models that describe the reaction via the natural-parity exchange of the K ∗ (892) Regge trajectory. A value of Σ = 0.41 ± 0.09 is obtained for the u channel integrated up to − u = 2.0 ( GeV / c ) 2 .

Published
2020

3. Beam asymmetry Σ for the photoproduction of η and η′ mesons at Eγ=8.8GeV

Author

A. Hurley, L. Gan, C. A. Meyer, J. Frye, C. Paudel, V. V. Tarasov, A. Dolgolenko, H. Hakobyan, C. Salgado, A. M. Schertz, E. Barriga, T. Daniels, C. Fanelli, R. T. Jones, W. Phelps, F. Nerling, M. E. McCracken, Krisztian Peters, Michael Dugger, V. Kakoyan, M. J. Staib, B. E. Cannon, T. Erbora, E. Pooser, I. A. Semenova, Z. Zhang, V. A. Matveev, A. Barnes, Dmitri Romanov, Sean A Dobbs, V. V. Berdnikov, A. Hamdi, J. Barlow, I. I. Strakovsky, Mark Richard James Williams, K. Suresh, T. Whitlatch, A. Somov, T. C. Black, D. Lawrence, A. Thiel, M. M. Dalton, H. Marukyan, Hovanes Egiyan, L. Ng, A. Ernst, M. McCaughan, R.S. Pedroni, W. McGinley, G. M. Huber, D. I. Sober, L. Robison, K. Livingston, V. Lyubovitskij, A. Deur, Ting Xiao, Q. Zhou, R. A. Miskimen, William Brooks, X. Zhou, P. Eugenio, G. Zhao, N. Wickramaarachchi, O. Cortes, N. Qin, L. Guo, E. Chudakov, R. Barsotti, Lubomir Pentchev, N. Cao, O. Soto, K. K. Seth, R. Dzhygadlo, F. Barbosa, B. Zihlmann, S. Fegan, M. Kamel, A. M. Foda, D. J. Mack, R. A. Schumacher, N. Gevorgyan, T. Britton, A. I. Ostrovidov, B. Liu, V. Crede, C.P. Romero, G. J. Lolos, I. Larin, G. Vasileiadis, H. Li, Ashot Gasparian, Sergey Kuleshov, D. I. Lersch, D. G. Ireland, A. Goncalves, Z. Papandreou, V. S. Goryachev, M. J. Amaryan, P. Mattione, S. Adhikari, M. Patsyuk, W. B. Li, A. Yu. Semenov, R. Dotel, Elton Smith, J. Schwiening, Barry Ritchie, J. R. Stevens, S. Somov, M. Boer, J. Foote, J. Zarling, M. R. Shepherd, A. Teymurazyan, C. Gleason, G. Kalicy, N. S. Jarvis, X. Shen, A. Austregesilo, S. Cole, Christine Kourkoumelis, Joerg Reinhold, A. Ali, R. E. Mitchell, W. U. Boeglin, Y. Yang, M. M. Ito, P. Pauli, S. Furletov, W. J. Briscoe, T. D. Beattie, and K. Goetzen

Subjects
Physics, GlueX, Meson, 010308 nuclear & particles physics, Linear polarization, media_common.quotation_subject, Momentum transfer, Parity (physics), 01 natural sciences, 7. Clean energy, Asymmetry, 0103 physical sciences, Quasiparticle, Atomic physics, Photon beam, 010306 general physics, media_common
Abstract

We report on the measurement of the beam asymmetry Σ for the reactions → γ p → p η and → γ p → p η ′ from the GlueX experiment using an 8.2–8.8-GeV linearly polarized tagged photon beam incident on a liquid hydrogen target in Hall D at Jefferson Laboratory. These measurements are made as a function of momentum transfer − t with significantly higher statistical precision than our earlier η measurements and are the first measurements of η ′ in this energy range. We compare the results to theoretical predictions based on t -channel quasiparticle exchange. We also compare the ratio of Σ η to Σ η ′ to these models as this ratio is predicted to be sensitive to the amount of s ¯ s exchange in the production. We find that photoproduction of both η and η ′ is dominated by natural parity exchange with little dependence on − t .

Published
2019

4. 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

5. 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

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

Author

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

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

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

Published
2017

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. 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

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