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1. A glimpse of gluons through deeply virtual compton scattering on the proton

Author

M. Defurne, A. Martí Jiménez-Argüello, Z. Ahmed, H. Albataineh, K. Allada, K. A. Aniol, V. Bellini, M. Benali, W. Boeglin, P. Bertin, M. Brossard, A. Camsonne, M. Canan, S. Chandavar, C. Chen, J.-P. Chen, C. W. de Jager, R. de Leo, C. Desnault, A. Deur, L. El Fassi, R. Ent, D. Flay, M. Friend, E. Fuchey, S. Frullani, F. Garibaldi, D. Gaskell, A. Giusa, O. Glamazdin, S. Golge, J. Gomez, O. Hansen, D. Higinbotham, T. Holmstrom, T. Horn, J. Huang, M. Huang, C. E. Hyde, S. Iqbal, F. Itard, H. Kang, A. Kelleher, C. Keppel, S. Koirala, I. Korover, J. J. LeRose, R. Lindgren, E. Long, M. Magne, J. Mammei, D. J. Margaziotis, P. Markowitz, M. Mazouz, F. Meddi, D. Meekins, R. Michaels, M. Mihovilovic, C. Muñoz Camacho, P. Nadel-Turonski, N. Nuruzzaman, R. Paremuzyan, A. Puckett, V. Punjabi, Y. Qiang, A. Rakhman, M. N. H. Rashad, S. Riordan, J. Roche, G. Russo, F. Sabatié, K. Saenboonruang, A. Saha, B. Sawatzky, L. Selvy, A. Shahinyan, S. Sirca, P. Solvignon, M. L. Sperduto, R. Subedi, V. Sulkosky, C. Sutera, W. A. Tobias, G. M. Urciuoli, D. Wang, B. Wojtsekhowski, H. Yao, Z. Ye, X. Zhan, J. Zhang, B. Zhao, Z. Zhao, X. Zheng, and P. Zhu

Subjects
Science
Abstract

It remains a challenge to find the structure and the distribution of the constituents of nucleons. Here the authors use a scattering method to get information about the gluons and quarks inside a proton and separate the contribution of Bethe-Heitler from the deeply virtual Compton scattering process.

Published
2017
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2. Deep Exclusive Electroproduction of π0 at High Q2 in the Quark Valence Regime

Author

N. H. Saylor, D. Bulumulla, Wouter Deconinck, E. Pooser, L. Ye, B. Crowe, Weidong Li, B. P. Quinn, Y. Huang, Douglas Higinbotham, E. Fuchey, C. Ayerbe Gayoso, Y. Zhao, S. A. Wood, M. K. Jones, Darko Androić, Jie Liu, A. J. Sarty, Z. Ye, K. Hamilton, E. McClellan, M. E. Christy, A. Liyanage, J. Bane, F. Georges, O. F. Obretch, C. Gal, S. F. Ali, Bogdan Wojtsekhowski, P. M. King, C. Palatchi, F. Hauenstein, J. Roche, T. Averett, P. E. Reimer, J. P. Chen, G. M. Urciuoli, Franco Meddi, M. H. Shabestari, C. Fanelli, K. A. Aniol, R. I. Pomatsalyuk, B. Aljawrneh, Shams Rahman, C. E. Hyde, R. Beminiwattha, X. Yan, Andrew Puckett, E. Voutier, E. Cisbani, S. J. Nazeer, Chunhui Chen, C. Desnault, M. Carmignotto, O. Glamazdin, J. Castellano, Z. Ahmed, L. Ou, F. De Persio, Olfred Hansen, S. Allison, J. R. M. Annand, Simon Širca, T. Gautam, D. Nguyen, B. Sawatzky, G. M. Huber, S. Danagoulian, J. C. Cornejo, Tanja Horn, C. M. Jen, F. Tortorici, T. Su, S. Alsalmi, Yicheng Wang, G. Hamad, B. Duran, Kalyan Allada, Maxime Defurne, R. Michaels, Hongjun Liu, D. Gaskell, Juliette Mammei, David Hamilton, Pete Markowitz, L. A. Thorne, E. J. Brash, V. M. Gray, C. Munoz Camacho, D. Adikaram, T. W. Danley, Y. Tian, K. Park, Ping Zhu, L. S. Myers, M. N. H. Rashad, Rolf Ent, R. A. Montgomery, D. Biswas, S. Malace, W. Henry, A. Sun, M. Dlamini, H. Atac, N. Israel, R. Trotta, X. Bai, V. Bellini, N. Ton, R. Spies, Alexandre Camsonne, A. Stefanko, C. Gu, K. Bartlett, K. Jin, B. A. Clary, Kondo Gnanvo, M. Nycz, T. Holmstrom, P.-J. Lin, Shanfeng Li, C. Yero, T. Hague, Taya Chetry, Jie Zhang, J. Bericic, J. Campbell, A. Mkrtchyan, Nikos Sparveris, K. Mesik, I. Sapkota, Vladimir Nelyubin, A. Shahinyan, N. Compton, D. Di, Eliahu Cohen, S. Sooriyaarachchilage, Cynthia Keppel, H. S. Ko, A. Kabir, V. A. Punjabi, D. G. Meekins, S. Barcus, V. Khachatryan, G. B. Franklin, P. Nadel-Turonski, N. Nuruzzaman, Chao Peng, G. R. Smith, H. F. Ibrahim, B. Karki, M. Duer, H. Albataineh, A. Subedi, S. Park, B. Schmookler, B. Pandey, Vincent Sulkosky, J. A. Magee, B. Waidyawansa, and S. Covrig Dusa

Subjects
Quark, Physics, Particle physics, 010308 nuclear & particles physics, Momentum transfer, General Physics and Astronomy, Sigma, Virtual particle, Parton, 01 natural sciences, Helicity, Pion, 0103 physical sciences, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, Nucleon
Abstract

We report measurements of the exclusive neutral pion electroproduction cross section off protons at large values of $x_B$ (0.36, 0.48 and 0.60) and $Q^2$ (3.1 to 8.4 GeV$^2$) obtained from Jefferson Lab Hall A experiment E12-06-014. The corresponding structure functions $d\sigma_L/dt+\epsilon d\sigma_T/dt$, $d\sigma_{TT}/dt$, $d\sigma_{LT}/dt$ and $d\sigma_{LT'}/dt$ are extracted as a function of the proton momentum transfer $t-t_{min}$. The results suggest the amplitude for transversely polarized virtual photons continues to dominate the cross-section throughout this kinematic range. The data are well described by calculations based on transversity Generalized Parton Distributions coupled to a helicity flip Distribution Amplitude of the pion, thus providing a unique way to probe the structure of the nucleon.

Published
2021

3. Deeply virtual Compton scattering off the neutron

Author

M. Benali, C. Desnault, M. Mazouz, Z. Ahmed, H. Albataineh, K. Allada, K. A. Aniol, V. Bellini, W. Boeglin, P. Bertin, M. Brossard, A. Camsonne, M. Canan, S. Chandavar, C. Chen, J.-P. Chen, M. Defurne, C. W. de Jager, R. de Leo, A. Deur, L. El Fassi, R. Ent, D. Flay, M. Friend, E. Fuchey, S. Frullani, F. Garibaldi, D. Gaskell, A. Giusa, O. Glamazdin, S. Golge, J. Gomez, O. Hansen, D. Higinbotham, T. Holmstrom, T. Horn, J. Huang, M. Huang, G. M. Huber, C. E. Hyde, S. Iqbal, F. Itard, Ho. Kang, Hy. Kang, A. Kelleher, C. Keppel, S. Koirala, I. Korover, J. J. LeRose, R. Lindgren, E. Long, M. Magne, J. Mammei, D. J. Margaziotis, P. Markowitz, A. Martí Jiménez-Argüello, F. Meddi, D. Meekins, R. Michaels, M. Mihovilovic, N. Muangma, C. Muñoz Camacho, P. Nadel-Turonski, N. Nuruzzaman, R. Paremuzyan, R. Pomatsalyuk, A. Puckett, V. Punjabi, Y. Qiang, A. Rakhman, M. N. H. Rashad, S. Riordan, J. Roche, G. Russo, F. Sabatié, K. Saenboonruang, A. Saha, B. Sawatzky, L. Selvy, A. Shahinyan, S. Sirca, P. Solvignon, M. L. Sperduto, R. Subedi, V. Sulkosky, C. Sutera, W. A. Tobias, G. M. Urciuoli, D. Wang, B. Wojtsekhowski, H. Yao, Z. Ye, L. Zana, X. Zhan, J. Zhang, B. Zhao, Z. Zhao, X. Zheng, P. Zhu, Laboratoire de Physique de Clermont (LPC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), 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), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, 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 Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
quark: flavor, Astrophysics::High Energy Astrophysical Phenomena, High Energy Physics::Lattice, High Energy Physics::Phenomenology, Nuclear Theory, n: structure function, nucleon, FOS: Physical sciences, General Physics and Astronomy, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, High Energy Physics - Experiment, 010305 fluids & plasmas, High Energy Physics - Phenomenology, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology (hep-ph), deeply virtual Compton scattering, 0103 physical sciences, photon: scattering, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Experiment
Abstract

The three-dimensional structure of nucleons (protons and neutrons) is embedded in so-called generalized parton distributions, which are accessible from deeply virtual Compton scattering. In this process, a high energy electron is scattered off a nucleon by exchanging a virtual photon. Then, a highly-energetic real photon is emitted from one of the quarks inside the nucleon, which carries information on the quark's transverse position and longitudinal momentum. By measuring the cross-section of deeply virtual Compton scattering, Compton form factors related to the generalized parton distributions can be extracted. Here, we report the observation of unpolarized deeply virtual Compton scattering off a deuterium target. From the measured photon-electroproduction cross-sections, we have extracted the cross-section of a quasi-free neutron and a coherent deuteron. Due to the approximate isospin symmetry of quantum chromodynamics, we can determine the contributions from the different quark flavours to the helicity-conserved Compton form factors by combining our measurements with previous ones probing the proton's internal structure. These results advance our understanding of the description of the nucleon structure, which is important to solve the proton spin puzzle.

Published
2020

4. The Heavy Photon Search test detector

Author

H. A. Neal, Volker D. Burkert, Alexander Grillo, M. Ungaro, A. P. Freyberger, M. Oriunno, Ryan Herbst, E. Rindel, T. K. Nelson, R. Paremuzyan, A. Kubarovsky, S. Stepanyan, S. Bueltmann, M. Battaglieri, Bogdan Wojtsekhowski, Natalia Toro, S. K. Phillips, Y. G. Sharabian, William T. Cooper, J. Reichert, Larry Weinstein, C. Field, V. P. Kubarovsky, J. Jaros, F. X. Girod, B. Raydo, Jeremy McCormick, Matthew J. Graham, Yuri Gershtein, K. Moffeit, R. Partridge, Rouven Essig, N. Gevorgyan, Norman A. Graf, H. Voskanyan, C. Cuevas, C. Salgado, A. Odian, E. Rauly, G. Charles, C. Desnault, Andrea Celentano, S. Niccolai, M. Guidal, Latifa Elouadrhiri, S. Kaneta, M. Khandaker, N. Dashyan, M. Holtrop, R. DeVita, S. Uemura, P. Hansson Adrian, K. A. Griffioen, Omar Moreno, D. Sokhan, Hovanes Egiyan, Dieter Walz, Philip Schuster, Vitaliy Fadeyev, P. Rosier, A. Deur, S. Boyarinov, Gunther Haller, T. Maruyama, Institut de Physique Nucléaire d'Orsay (IPNO), and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nuclear and High Energy Physics, Silicon, Physics - Instrumentation and Detectors, Photon, Physics::Instrumentation and Detectors, FOS: Physical sciences, Tracking (particle physics), Dark photon, High Energy Physics - Experiment, law.invention, Nuclear physics, High Energy Physics - Experiment (hep-ex), Electromagnetic calorimeter, law, Dipole magnet, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Instrumentation, Physics, Calorimeter (particle physics), Tracking, Particle accelerator, Instrumentation and Detectors (physics.ins-det), Charged particle, Vertexing, Beamline, Heavy photon
Abstract

The Heavy Photon Search (HPS), an experiment to search for a hidden sector photon in fixed target electroproduction, is preparing for installation at the Thomas Jefferson National Accelerator Facility (JLab) in the Fall of 2014. As the first stage of this project, the HPS Test Run apparatus was constructed and operated in 2012 to demonstrate the experiment's technical feasibility and to confirm that the trigger rates and occupancies are as expected. This paper describes the HPS Test Run apparatus and readout electronics and its performance. In this setting, a heavy photon can be identified as a narrow peak in the e$^+$e$^-$ invariant mass spectrum, above the trident background or as a narrow invariant mass peak with a decay vertex displaced from the production target, so charged particle tracking and vertexing are needed for its detection. In the HPS Test Run, charged particles are measured with a compact forward silicon microstrip tracker inside a dipole magnet. Electromagnetic showers are detected in a PbW0$_{4}$ crystal calorimeter situated behind the magnet, and are used to trigger the experiment and identify electrons and positrons. Both detectors are placed close to the beam line and split top-bottom. This arrangement provides sensitivity to low-mass heavy photons, allows clear passage of the unscattered beam, and avoids the spray of degraded electrons coming from the target. The discrimination between prompt and displaced e$^+$e$^-$ pairs requires the first layer of silicon sensors be placed only 10~cm downstream of the target. The expected signal is small, and the trident background huge, so the experiment requires very large statistics. Accordingly, the HPS Test Run utilizes high-rate readout and data acquisition electronics and a fast trigger to exploit the essentially 100% duty cycle of the CEBAF accelerator at JLab., Comment: Revised version to match published version, 16 pages, 18 figures, published in Nuclear Instruments and Methods in Physics Research Section A, editor: Per Hansson Adrian

Published
2015
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5. Rosenbluth Separation of the π0 Electroproduction Cross Section Off the Neutron

Author

N. Nuruzzaman, S. Golge, M. L. Sperduto, Bogdan Wojtsekhowski, R. A. Lindgren, J. J. LeRose, C. M. Sutera, Chunhui Chen, Z. W. Zhao, Z. Ye, M. Mihovilovic, H. Albataineh, H. Yao, D. Flay, N. Muangma, V. Bellini, A. Martí Jiménez-Argüello, Yujie Qiang, A. Saha, M. Huang, Andrew Puckett, D. G. Meekins, Z. Ahmed, B. Zhao, F. Sabatié, Simon Širca, G. M. Huber, Pete Markowitz, S. Koirala, F. Garibaldi, L. El Fassi, W. U. Boeglin, C. E. Hyde, Tanja Horn, X. Zhan, D. J. Margaziotis, M. Brossard, S. Chandavar, Maxime Defurne, R. De Leo, D. Gaskell, M. Benali, C. W. de Jager, K. A. Aniol, M. Mazouz, P. Solvignon, O. Glamazdin, M. Magne, Olfred Hansen, A. Deur, Cynthia Keppel, A. Camsonne, Douglas Higinbotham, M. N. H. Rashad, A. Shahinyan, Vincent Sulkosky, V. A. Punjabi, Mustafa Canan, C. Desnault, Kalyan Allada, E. Long, J. Roche, S. Iqbal, William A. Tobias, E. Fuchey, I. Korover, A. Giusa, Abdurahim Rakhman, A. Kelleher, G.V. Russo, Ho. Kang, J. P. Chen, X. Zheng, L. Selvy, D. Wang, Juliette Mammei, L. Zana, J. Huang, G. M. Urciuoli, J. Gomez, Rolf Ent, S. Riordan, P.Y. Bertin, P. Nadel-Turonski, P. Zhu, H. Kang, Franco Meddi, M. Friend, Jie Zhang, S. Frullani, R. Paremuzyan, Kiadtisak Saenboonruang, R. Subedi, B. Sawatzky, F. Itard, T. Holmstrom, R. Michaels, and C. Munoz Camacho

Subjects
Quark, Physics, Particle physics, Meson, 010308 nuclear & particles physics, Nuclear Theory, Momentum transfer, General Physics and Astronomy, Parton, 01 natural sciences, 7. Clean energy, Nuclear physics, Recoil, 0103 physical sciences, Photon polarization, High Energy Physics::Experiment, Neutron, Nuclear Experiment, 010306 general physics, Nucleon
Abstract

We report the first longitudinal-transverse separation of the deeply virtual exclusive π^{0} electroproduction cross section off the neutron and coherent deuteron. The corresponding four structure functions dσ_{L}/dt, dσ_{T}/dt, dσ_{LT}/dt, and dσ_{TT}/dt are extracted as a function of the momentum transfer to the recoil system at Q^{2}=1.75 GeV^{2} and x_{B}=0.36. The ed→edπ^{0} cross sections are found compatible with the small values expected from theoretical models. The en→enπ^{0} cross sections show a dominance from the response to transversely polarized photons, and are in good agreement with calculations based on the transversity generalized parton distributions of the nucleon. By combining these results with previous measurements of π^{0} electroproduction off the proton, we present a flavor decomposition of the u and d quark contributions to the cross section.

Published
2017

6. Rosenbluth Separation of the π^{0} Electroproduction Cross Section Off the Neutron

Author

M, Mazouz, Z, Ahmed, H, Albataineh, K, Allada, K A, Aniol, V, Bellini, M, Benali, W, Boeglin, P, Bertin, M, Brossard, A, Camsonne, M, Canan, S, Chandavar, C, Chen, J-P, Chen, M, Defurne, C W, de Jager, R, de Leo, C, Desnault, A, Deur, L, El Fassi, R, Ent, D, Flay, M, Friend, E, Fuchey, S, Frullani, F, Garibaldi, D, Gaskell, A, Giusa, O, Glamazdin, S, Golge, J, Gomez, O, Hansen, D, Higinbotham, T, Holmstrom, T, Horn, J, Huang, M, Huang, G M, Huber, C E, Hyde, S, Iqbal, F, Itard, Ho, Kang, Hy, Kang, A, Kelleher, C, Keppel, S, Koirala, I, Korover, J J, LeRose, R, Lindgren, E, Long, M, Magne, J, Mammei, D J, Margaziotis, P, Markowitz, A, Martí Jiménez-Argüello, F, Meddi, D, Meekins, R, Michaels, M, Mihovilovic, N, Muangma, C, Muñoz Camacho, P, Nadel-Turonski, N, Nuruzzaman, R, Paremuzyan, A, Puckett, V, Punjabi, Y, Qiang, A, Rakhman, M N H, Rashad, S, Riordan, J, Roche, G, Russo, F, Sabatié, K, Saenboonruang, A, Saha, B, Sawatzky, L, Selvy, A, Shahinyan, S, Sirca, P, Solvignon, M L, Sperduto, R, Subedi, V, Sulkosky, C, Sutera, W A, Tobias, G M, Urciuoli, D, Wang, B, Wojtsekhowski, H, Yao, Z, Ye, L, Zana, X, Zhan, J, Zhang, B, Zhao, Z, Zhao, X, Zheng, and P, Zhu

Abstract

We report the first longitudinal-transverse separation of the deeply virtual exclusive π^{0} electroproduction cross section off the neutron and coherent deuteron. The corresponding four structure functions dσ_{L}/dt, dσ_{T}/dt, dσ_{LT}/dt, and dσ_{TT}/dt are extracted as a function of the momentum transfer to the recoil system at Q^{2}=1.75 GeV^{2} and x_{B}=0.36. The ed→edπ^{0} cross sections are found compatible with the small values expected from theoretical models. The en→enπ^{0} cross sections show a dominance from the response to transversely polarized photons, and are in good agreement with calculations based on the transversity generalized parton distributions of the nucleon. By combining these results with previous measurements of π^{0} electroproduction off the proton, we present a flavor decomposition of the u and d quark contributions to the cross section.

Published
2017

7. A glimpse of gluons through deeply virtual compton scattering on the proton

Author

J. Huang, S. Riordan, M. Brossard, I. Korover, N. Nuruzzaman, S. Golge, H. Al-Bataineh, P. Bertin, William A. Tobias, Abdurahim Rakhman, H. Kang, H. Yao, A. Camsonne, Franco Meddi, Yujie Qiang, M. Huang, A. Kelleher, A. Martí Jiménez-Argüello, S. Koirala, Kiadtisak Saenboonruang, D. J. Margaziotis, Andrew Puckett, T. Horn, E. Fuchey, G.V. Russo, R. Ent, Z. W. Zhao, Z. Ye, S. Chandavar, J. LeRose, R. De Leo, O. Glamazdin, Olfred Hansen, E. Long, F. Garibaldi, V. Bellini, L. Selvy, Bogdan Wojtsekhowski, M. N. H. Rashad, R. A. Lindgren, Cynthia Keppel, P. Markowitz, Jian-Ping Chen, X. Zhan, M. Mihovilovic, Juliette Mammei, Arijit Saha, J. Gomez, V. A. Punjabi, S. Frullani, P. Nadel-Turonski, Alexandre Deur, K. A. Aniol, Chunhui Chen, S. Širca, D. Wang, F. Sabatié, X. Zheng, R. Paremuzyan, Ping Zhu, Mustafa Canan, Kalyan Allada, R. Michaels, D. G. Meekins, C. M. Sutera, M. L. Sperduto, M. Magne, Charles Hyde, B. Zhao, D. Flay, P. Solvignon, L. El Fassi, W. U. Boeglin, M. Defurne, M. Mazouz, Jie Zhang, B. Sawatzky, M. Benali, C. Desnault, Vincent Sulkosky, S. Iqbal, F. Itard, J. Roche, M. Friend, T. Holmstrom, D. Gaskell, Douglas Higinbotham, A. Giusa, A. Shahinyan, C. W. de Jager, C. Muñoz Camacho, Z. Ahmed, G. M. Urciuoli, R. Subedi, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique de Clermont (LPC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers ( IRFU ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay ( IPNO ), Université Paris-Sud - Paris 11 ( UP11 ) -Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire de Physique de Clermont ( LPC ), and Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Université Clermont Auvergne ( UCA ) -Centre National de la Recherche Scientifique ( CNRS )

Subjects
Genetics and Molecular Biology (all), Photon, Proton, High Energy Physics::Lattice, Nuclear Theory, General Physics and Astronomy, Virtual particle, parton: distribution function, Biochemistry, 01 natural sciences, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology (hep-ph), [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], p: structure function, Nuclear Experiment (nucl-ex), [ PHYS.NEXP ] Physics [physics]/Nuclear Experiment [nucl-ex], lcsh:Science, Nuclear Experiment, Physics, energy: high, Multidisciplinary, strong interaction, Chemistry (all), Compton scattering: form factor, photon: energy spectrum, High Energy Physics - Phenomenology, confinement, +electron+p+photon%22">electron p --> electron p photon, channel cross section: measured, Quark, electron p: deep inelastic scattering, Particle physics, electron: polarized beam, Science, Strong interaction, FOS: Physical sciences, Bethe-Heitler, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Article, General Biochemistry, Genetics and Molecular Biology, energy dependence, quark, Physics and Astronomy (all), [ PHYS.HEXP ] Physics [physics]/High Energy Physics - Experiment [hep-ex], photon: emission, deeply virtual Compton scattering, 0103 physical sciences, structure, 010306 general physics, quantum mechanics: interference, 010308 nuclear & particles physics, High Energy Physics::Phenomenology, Compton scattering, General Chemistry, gluon, sensitivity, Gluon, [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph], Quark–gluon plasma, lcsh:Q, [ PHYS.HPHE ] Physics [physics]/High Energy Physics - Phenomenology [hep-ph], High Energy Physics::Experiment, holography, Biochemistry, Genetics and Molecular Biology (all), photon: virtual, experimental results
Abstract

The internal structure of nucleons (protons and neutrons) remains one of the greatest outstanding problems in modern nuclear physics. By scattering high-energy electrons off a proton we are able to resolve its fundamental constituents and probe their momenta and positions. Here we investigate the dynamics of quarks and gluons inside nucleons using deeply virtual Compton scattering (DVCS)—a highly virtual photon scatters off the proton, which subsequently radiates a photon. DVCS interferes with the Bethe-Heitler (BH) process, where the photon is emitted by the electron rather than the proton. We report herein the full determination of the BH-DVCS interference by exploiting the distinct energy dependences of the DVCS and BH amplitudes. In the regime where the scattering is expected to occur off a single quark, measurements show an intriguing sensitivity to gluons, the carriers of the strong interaction., It remains a challenge to find the structure and the distribution of the constituents of nucleons. Here the authors use a scattering method to get information about the gluons and quarks inside a proton and separate the contribution of Bethe-Heitler from the deeply virtual Compton scattering process.

Published
2017

8. Rosenbluth Separation of the π^{0} Electroproduction Cross Section

Author

M. Brossard, E. Long, William A. Tobias, A. Kelleher, A. Saha, D. J. Margaziotis, Pete Markowitz, Bogdan Wojtsekhowski, D. G. Meekins, R. Subedi, O. Glamazdin, Chunhui Chen, S. Chandavar, C. M. Sutera, F. Sabatié, R. De Leo, Olfred Hansen, Maxime Defurne, J. P. Chen, Kiadtisak Saenboonruang, L. El Fassi, W. U. Boeglin, N. Nuruzzaman, B. Sawatzky, Abdurahim Rakhman, S. Golge, M. Magne, M. N. H. Rashad, J. Huang, G. M. Urciuoli, M. Friend, S. Koirala, A. Martí Jiménez-Argüello, S. Riordan, C. W. de Jager, K. A. Aniol, P. Nadel-Turonski, Yujie Qiang, H. Yao, R. A. Lindgren, J. J. LeRose, Andrew Puckett, A. Deur, C. E. Hyde, I. Korover, R. Michaels, Cynthia Keppel, X. Zhan, Z. W. Zhao, Z. Ye, E. Fuchey, Jie Zhang, V. A. Punjabi, P.Y. Bertin, C. Desnault, H. Albataineh, P. Zhu, M. Mazouz, Z. Ahmed, Ho. Kang, G.V. Russo, L. Selvy, R. Paremuzyan, D. Flay, X. Zheng, S. Frullani, V. Bellini, L. Zana, M. Huang, Simon Širca, G. M. Huber, F. Garibaldi, H. Kang, M. Benali, A. Camsonne, Vincent Sulkosky, Juliette Mammei, Franco Meddi, Rolf Ent, J. Roche, D. Gaskell, J. Gomez, M. L. Sperduto, A. Shahinyan, P. Solvignon, Mustafa Canan, Kalyan Allada, M. Mihovilovic, N. Muangma, S. Iqbal, D. Wang, Douglas Higinbotham, F. Itard, T. Holmstrom, C. Muñoz Camacho, B. Zhao, A. Giusa, Tanja Horn, Département de Physique des Particules (ex SPP) (DPhP), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Jefferson Lab Hall A

Subjects
Particle physics, longitudinal, interference, General Physics and Astronomy, parton: distribution function, Parton, hard exclusive electroproduction, mesons, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, High Energy Physics - Experiment, Nuclear physics, pi: distribution amplitude, generalized parton distribution: transversity, Pion, deep inelastic scattering, 0103 physical sciences, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], quantum chromodynamics: perturbation theory, 010306 general physics, Nuclear Experiment, Quantum chromodynamics, Physics, 010308 nuclear & particles physics, scattering amplitude, momentum transfer, Sigma, nucleon: generalized parton distribution, Scattering amplitude, transverse, Distribution (mathematics), Amplitude, pi0: electroproduction, twist, High Energy Physics::Experiment, Nucleon, channel cross section: measured, Jefferson Lab, experimental results
Abstract

We present deeply virtual $\pi^0$ electroproduction cross-section measurements at $x_B$=0.36 and three different $Q^2$--values ranging from 1.5 to 2 GeV$^2$, obtained from experiment E07-007 that ran in the Hall A at Jefferson Lab. The Rosenbluth technique was used to separate the longitudinal and transverse responses. Results demonstrate that the cross section is dominated by its transverse component, and thus is far from the asymptotic limit predicted by perturbative Quantum Chromodynamics. An indication of a non-zero longitudinal contribution is provided by the interference term $\sigma_{LT}$ also measured. Results are compared with several models based on the leading twist approach of Generalized Parton Distributions (GPDs). In particular, a fair agreement is obtained with models where the scattering amplitude is described by a convolution of chiral-odd (transversity) GPDs of the nucleon with the twist-3 pion distribution amplitude. Therefore, neutral pion electroproduction may offer the exciting possibility of accessing transversity GPDs through experiment., Comment: Submitted to Physical Review Letters

Published
2016

9. Deeply virtual compton scattering off the neutron

Author

B. Zhao, Rolf Ent, P. Solvignon, V. Bellini, Mustafa Canan, Kalyan Allada, Tanja Horn, P. Nadel-Turonski, S. Koirala, G.V. Russo, C. M. Sutera, J. P. Chen, M. N. H. Rashad, Simon Širca, J. Huang, G. M. Urciuoli, A. Shahinyan, S. Iqbal, G. M. Huber, F. Garibaldi, M. Friend, Douglas Higinbotham, D. J. Margaziotis, Kiadtisak Saenboonruang, M. L. Sperduto, Maxime Defurne, F. Itard, Cynthia Keppel, L. Selvy, N. Muangma, Ho. Kang, T. Holmstrom, L. Zana, Pete Markowitz, R. I. Pomatsalyuk, V. A. Punjabi, Arijit Saha, William A. Tobias, B. Sawatzky, Abdurahim Rakhman, Chunhui Chen, M. Huang, Juliette Mammei, J. LeRose, F. Sabatié, X. Zhan, R. De Leo, A. Giusa, M. Benali, H. Yao, R. Michaels, A. Kelleher, Jie Zhang, A. Camsonne, I. Korover, H. Kang, C. Munoz Camacho, M. Mazouz, A. Deur, M. Brossard, M. Mihovilovic, D. Wang, S. Frullani, Vincent Sulkosky, R. Paremuzyan, E. Fuchey, R. A. Lindgren, S. Riordan, Franco Meddi, C. Desnault, H. Albataineh, D. Flay, J. Roche, Bogdan Wojtsekhowski, S. Chandavar, P. Bertin, C. W. de Jager, K. A. Aniol, R. Subedi, D. G. Meekins, P. Zhu, Z. Ahmed, L. El Fassi, W. U. Boeglin, E. Long, J. Gomez, O. Glamazdin, Olfred Hansen, A. Martí Jiménez-Argüello, Yujie Qiang, Andrew Puckett, X. Zheng, David Gaskell, Z. W. Zhao, Z. Ye, M. Magne, Charles Hyde, N. Nuruzzaman, S. Golge, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), HALL A, 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), and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11)

Subjects
Quark, Physics, Particle physics, Photon, 010308 nuclear & particles physics, Scattering, High Energy Physics::Phenomenology, Nuclear Theory, Compton scattering, FOS: Physical sciences, General Physics and Astronomy, Virtual particle, Parton, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Nuclear physics, Isospin, 0103 physical sciences, 25.30.-c, 13.60.Fz, 13.85.Hd, 14.20.Dh, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), 010306 general physics, Nucleon, Nuclear Experiment
Abstract

The present experiment exploits the interference between the Deeply Virtual Compton Scattering (DVCS) and the Bethe-Heitler processes to extract the imaginary part of DVCS amplitudes on the neutron and on the deuteron from the helicity-dependent D$({\vec e},e'\gamma)X$ cross section measured at $Q^2$=1.9 GeV$^2$ and $x_B$=0.36. We extract a linear combination of generalized parton distributions (GPDs) particularly sensitive to $E_q$, the least constrained GPD. A model dependent constraint on the contribution of the up and down quarks to the nucleon spin is deduced., Comment: Published in Phys. Rev. Lett

Published
2007

10. Deeply Virtual Compton Scattering Cross Section at High Bjorken x_{B}.

Author

Georges F, Rashad MNH, Stefanko A, Dlamini M, Karki B, Ali SF, Lin PJ, Ko HS, Israel N, Adikaram D, Ahmed Z, Albataineh H, Aljawrneh B, Allada K, Allison S, Alsalmi S, Androic D, Aniol K, Annand J, Atac H, Averett T, Ayerbe Gayoso C, Bai X, Bane J, Barcus S, Bartlett K, Bellini V, Beminiwattha R, Bericic J, Biswas D, Brash E, Bulumulla D, Campbell J, Camsonne A, Carmignotto M, Castellano J, Chen C, Chen JP, Chetry T, Christy ME, Cisbani E, Clary B, Cohen E, Compton N, Cornejo JC, Covrig Dusa S, Crowe B, Danagoulian S, Danley T, De Persio F, Deconinck W, Defurne M, Desnault C, Di D, Duer M, Duran B, Ent R, Fanelli C, Franklin G, Fuchey E, Gal C, Gaskell D, Gautam T, Glamazdin O, Gnanvo K, Gray VM, Gu C, Hague T, Hamad G, Hamilton D, Hamilton K, Hansen O, Hauenstein F, Henry W, Higinbotham DW, Holmstrom T, Horn T, Huang Y, Huber GM, Hyde CE, Ibrahim H, Jen CM, Jin K, Jones M, Kabir A, Keppel C, Khachatryan V, King PM, Li S, Li WB, Liu J, Liu H, Liyanage A, Magee J, Malace S, Mammei J, Markowitz P, McClellan E, Mazouz M, Meddi F, Meekins D, Mesik K, Michaels R, Mkrtchyan A, Montgomery R, Muñoz Camacho C, Myers LS, Nadel-Turonski P, Nazeer SJ, Nelyubin V, Nguyen D, Nuruzzaman N, Nycz M, Obretch OF, Ou L, Palatchi C, Pandey B, Park S, Park K, Peng C, Pomatsalyuk R, Pooser E, Puckett AJR, Punjabi V, Quinn B, Rahman S, Reimer PE, Roche J, Sapkota I, Sarty A, Sawatzky B, Saylor NH, Schmookler B, Shabestari MH, Shahinyan A, Sirca S, Smith GR, Sooriyaarachchilage S, Sparveris N, Spies R, Su T, Subedi A, Sulkosky V, Sun A, Thorne L, Tian Y, Ton N, Tortorici F, Trotta R, Urciuoli GM, Voutier E, Waidyawansa B, Wang Y, Wojtsekhowski B, Wood S, Yan X, Ye L, Ye Z, Yero C, Zhang J, Zhao Y, and Zhu P

Abstract

We report high-precision measurements of the deeply virtual Compton scattering (DVCS) cross section at high values of the Bjorken variable x_{B}. DVCS is sensitive to the generalized parton distributions of the nucleon, which provide a three-dimensional description of its internal constituents. Using the exact analytic expression of the DVCS cross section for all possible polarization states of the initial and final electron and nucleon, and final state photon, we present the first experimental extraction of all four helicity-conserving Compton form factors (CFFs) of the nucleon as a function of x_{B}, while systematically including helicity flip amplitudes. In particular, the high accuracy of the present data demonstrates sensitivity to some very poorly known CFFs.

Published
2022
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11. Form Factors and Two-Photon Exchange in High-Energy Elastic Electron-Proton Scattering.

Author

Christy ME, Gautam T, Ou L, Schmookler B, Wang Y, Adikaram D, Ahmed Z, Albataineh H, Ali SF, Aljawrneh B, Allada K, Allison SL, Alsalmi S, Androic D, Aniol K, Annand J, Arrington J, Atac H, Averett T, Ayerbe Gayoso C, Bai X, Bane J, Barcus S, Bartlett K, Bellini V, Beminiwattha R, Bericic J, Bhatt H, Bhetuwal D, Biswas D, Brash E, Bulumulla D, Camacho CM, Campbell J, Camsonne A, Carmignotto M, Castellanos J, Chen C, Chen JP, Chetry T, Cisbani E, Clary B, Cohen E, Compton N, Cornejo JC, Covrig Dusa S, Crowe B, Danagoulian S, Danley T, Deconinck W, Defurne M, Desnault C, Di D, Dlamini M, Duer M, Duran B, Ent R, Fanelli C, Fuchey E, Gal C, Gaskell D, Georges F, Gilad S, Glamazdin O, Gnanvo K, Gramolin AV, Gray VM, Gu C, Habarakada A, Hague T, Hamad G, Hamilton D, Hamilton K, Hansen O, Hauenstein F, Hernandez AV, Henry W, Higinbotham DW, Holmstrom T, Horn T, Huang Y, Huber GM, Hyde C, Ibrahim H, Israel N, Jen CM, Jin K, Jones M, Kabir A, Karki B, Keppel C, Khachatryan V, King PM, Li S, Li W, Liu H, Liu J, Liyanage AH, Mack D, Magee J, Malace S, Mammei J, Markowitz P, Mayilyan S, McClellan E, Meddi F, Meekins D, Mesick K, Michaels R, Mkrtchyan A, Moffit B, Montgomery R, Myers LS, Nadel-Turonski P, Nazeer SJ, Nelyubin V, Nguyen D, Nuruzzaman N, Nycz M, Obrecht RF, Ohanyan K, Palatchi C, Pandey B, Park K, Park S, Peng C, Persio FD, Pomatsalyuk R, Pooser E, Puckett AJR, Punjabi V, Quinn B, Rahman S, Rashad MNH, Reimer PE, Riordan S, Roche J, Sapkota I, Sarty A, Sawatzky B, Saylor NH, Shabestari MH, Shahinyan A, Širca S, Smith GR, Sooriyaarachchilage S, Sparveris N, Spies R, Stefanko A, Su T, Subedi A, Sulkosky V, Sun A, Tan Y, Thorne L, Ton N, Tortorici F, Trotta R, Uniyal R, Urciuoli GM, Voutier E, Waidyawansa B, Wojtsekhowski B, Wood S, Yan X, Ye L, Ye ZH, Yero C, Zhang J, Zhao YX, and Zhu P

Abstract

We present new precision measurements of the elastic electron-proton scattering cross section for momentum transfer (Q^{2}) up to 15.75  (GeV/c)^{2}. Combined with existing data, these provide an improved extraction of the proton magnetic form factor at high Q^{2} and double the range over which a longitudinal or transverse separation of the cross section can be performed. The difference between our results and polarization data agrees with that observed at lower Q^{2} and attributed to hard two-photon exchange (TPE) effects, extending to 8  (GeV/c)^{2} the range of Q^{2} for which a discrepancy is established at >95% confidence. We use the discrepancy to quantify the size of TPE contributions needed to explain the cross section at high Q^{2}.

Published
2022
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12. Deep Exclusive Electroproduction of π^{0} at High Q^{2} in the Quark Valence Regime.

Author

Dlamini M, Karki B, Ali SF, Lin PJ, Georges F, Ko HS, Israel N, Rashad MNH, Stefanko A, Adikaram D, Ahmed Z, Albataineh H, Aljawrneh B, Allada K, Allison S, Alsalmi S, Androic D, Aniol K, Annand J, Atac H, Averett T, Ayerbe Gayoso C, Bai X, Bane J, Barcus S, Bartlett K, Bellini V, Beminiwattha R, Bericic J, Biswas D, Brash E, Bulumulla D, Campbell J, Camsonne A, Carmignotto M, Castellano J, Chen C, Chen JP, Chetry T, Christy ME, Cisbani E, Clary B, Cohen E, Compton N, Cornejo JC, Covrig Dusa S, Crowe B, Danagoulian S, Danley T, De Persio F, Deconinck W, Defurne M, Desnault C, Di D, Duer M, Duran B, Ent R, Fanelli C, Franklin G, Fuchey E, Gal C, Gaskell D, Gautam T, Glamazdin O, Gnanvo K, Gray VM, Gu C, Hague T, Hamad G, Hamilton D, Hamilton K, Hansen O, Hauenstein F, Henry W, Higinbotham DW, Holmstrom T, Horn T, Huang Y, Huber GM, Hyde C, Ibrahim H, Jen CM, Jin K, Jones M, Kabir A, Keppel C, Khachatryan V, King PM, Li S, Li W, Liu J, Liu H, Liyanage A, Magee J, Malace S, Mammei J, Markowitz P, McClellan E, Meddi F, Meekins D, Mesik K, Michaels R, Mkrtchyan A, Montgomery R, Muñoz Camacho C, Myers LS, Nadel-Turonski P, Nazeer SJ, Nelyubin V, Nguyen D, Nuruzzaman N, Nycz M, Obretch OF, Ou L, Palatchi C, Pandey B, Park S, Park K, Peng C, Pomatsalyuk R, Pooser E, Puckett AJR, Punjabi V, Quinn B, Rahman S, Reimer PE, Roche J, Sapkota I, Sarty A, Sawatzky B, Saylor NH, Schmookler B, Shabestari MH, Shahinyan A, Sirca S, Smith GR, Sooriyaarachchilage S, Sparveris N, Spies R, Su T, Subedi A, Sulkosky V, Sun A, Thorne L, Tian Y, Ton N, Tortorici F, Trotta R, Urciuoli GM, Voutier E, Waidyawansa B, Wang Y, Wojtsekhowski B, Wood S, Yan X, Ye L, Ye Z, Yero C, Zhang J, Zhao Y, and Zhu P

Abstract

We report measurements of the exclusive neutral pion electroproduction cross section off protons at large values of x_{B} (0.36, 0.48, and 0.60) and Q^{2} (3.1 to 8.4  GeV^{2}) obtained from Jefferson Lab Hall A experiment E12-06-014. The corresponding structure functions dσ_{T}/dt+εdσ_{L}/dt, dσ_{TT}/dt, dσ_{LT}/dt, and dσ_{LT^{'}}/dt are extracted as a function of the proton momentum transfer t-t_{min}. The results suggest the amplitude for transversely polarized virtual photons continues to dominate the cross section throughout this kinematic range. The data are well described by calculations based on transversity generalized parton distributions coupled to a helicity flip distribution amplitude of the pion, thus providing a unique way to probe the structure of the nucleon.

Published
2021
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13. A glimpse of gluons through deeply virtual compton scattering on the proton.

Author

Defurne M, Jiménez-Argüello AM, Ahmed Z, Albataineh H, Allada K, Aniol KA, Bellini V, Benali M, Boeglin W, Bertin P, Brossard M, Camsonne A, Canan M, Chandavar S, Chen C, Chen JP, de Jager CW, de Leo R, Desnault C, Deur A, El Fassi L, Ent R, Flay D, Friend M, Fuchey E, Frullani S, Garibaldi F, Gaskell D, Giusa A, Glamazdin O, Golge S, Gomez J, Hansen O, Higinbotham D, Holmstrom T, Horn T, Huang J, Huang M, Hyde CE, Iqbal S, Itard F, Kang H, Kelleher A, Keppel C, Koirala S, Korover I, LeRose JJ, Lindgren R, Long E, Magne M, Mammei J, Margaziotis DJ, Markowitz P, Mazouz M, Meddi F, Meekins D, Michaels R, Mihovilovic M, Camacho CM, Nadel-Turonski P, Nuruzzaman N, Paremuzyan R, Puckett A, Punjabi V, Qiang Y, Rakhman A, Rashad MNH, Riordan S, Roche J, Russo G, Sabatié F, Saenboonruang K, Saha A, Sawatzky B, Selvy L, Shahinyan A, Sirca S, Solvignon P, Sperduto ML, Subedi R, Sulkosky V, Sutera C, Tobias WA, Urciuoli GM, Wang D, Wojtsekhowski B, Yao H, Ye Z, Zhan X, Zhang J, Zhao B, Zhao Z, Zheng X, and Zhu P

Abstract

The internal structure of nucleons (protons and neutrons) remains one of the greatest outstanding problems in modern nuclear physics. By scattering high-energy electrons off a proton we are able to resolve its fundamental constituents and probe their momenta and positions. Here we investigate the dynamics of quarks and gluons inside nucleons using deeply virtual Compton scattering (DVCS)-a highly virtual photon scatters off the proton, which subsequently radiates a photon. DVCS interferes with the Bethe-Heitler (BH) process, where the photon is emitted by the electron rather than the proton. We report herein the full determination of the BH-DVCS interference by exploiting the distinct energy dependences of the DVCS and BH amplitudes. In the regime where the scattering is expected to occur off a single quark, measurements show an intriguing sensitivity to gluons, the carriers of the strong interaction.

Published
2017
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14. Rosenbluth Separation of the π^{0} Electroproduction Cross Section Off the Neutron.

Author

Mazouz M, Ahmed Z, Albataineh H, Allada K, Aniol KA, Bellini V, Benali M, Boeglin W, Bertin P, Brossard M, Camsonne A, Canan M, Chandavar S, Chen C, Chen JP, Defurne M, de Jager CW, de Leo R, Desnault C, Deur A, El Fassi L, Ent R, Flay D, Friend M, Fuchey E, Frullani S, Garibaldi F, Gaskell D, Giusa A, Glamazdin O, Golge S, Gomez J, Hansen O, Higinbotham D, Holmstrom T, Horn T, Huang J, Huang M, Huber GM, Hyde CE, Iqbal S, Itard F, Kang H, Kang H, Kelleher A, Keppel C, Koirala S, Korover I, LeRose JJ, Lindgren R, Long E, Magne M, Mammei J, Margaziotis DJ, Markowitz P, Martí Jiménez-Argüello A, Meddi F, Meekins D, Michaels R, Mihovilovic M, Muangma N, Muñoz Camacho C, Nadel-Turonski P, Nuruzzaman N, Paremuzyan R, Puckett A, Punjabi V, Qiang Y, Rakhman A, Rashad MNH, Riordan S, Roche J, Russo G, Sabatié F, Saenboonruang K, Saha A, Sawatzky B, Selvy L, Shahinyan A, Sirca S, Solvignon P, Sperduto ML, Subedi R, Sulkosky V, Sutera C, Tobias WA, Urciuoli GM, Wang D, Wojtsekhowski B, Yao H, Ye Z, Zana L, Zhan X, Zhang J, Zhao B, Zhao Z, Zheng X, and Zhu P

Abstract

We report the first longitudinal-transverse separation of the deeply virtual exclusive π^{0} electroproduction cross section off the neutron and coherent deuteron. The corresponding four structure functions dσ_{L}/dt, dσ_{T}/dt, dσ_{LT}/dt, and dσ_{TT}/dt are extracted as a function of the momentum transfer to the recoil system at Q^{2}=1.75  GeV^{2} and x_{B}=0.36. The ed→edπ^{0} cross sections are found compatible with the small values expected from theoretical models. The en→enπ^{0} cross sections show a dominance from the response to transversely polarized photons, and are in good agreement with calculations based on the transversity generalized parton distributions of the nucleon. By combining these results with previous measurements of π^{0} electroproduction off the proton, we present a flavor decomposition of the u and d quark contributions to the cross section.

Published
2017
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15. Rosenbluth Separation of the π^{0} Electroproduction Cross Section.

Author

Defurne M, Mazouz M, Ahmed Z, Albataineh H, Allada K, Aniol KA, Bellini V, Benali M, Boeglin W, Bertin P, Brossard M, Camsonne A, Canan M, Chandavar S, Chen C, Chen JP, de Jager CW, de Leo R, Desnault C, Deur A, El Fassi L, Ent R, Flay D, Friend M, Fuchey E, Frullani S, Garibaldi F, Gaskell D, Giusa A, Glamazdin O, Golge S, Gomez J, Hansen O, Higinbotham D, Holmstrom T, Horn T, Huang J, Huang M, Huber GM, Hyde CE, Iqbal S, Itard F, Kang H, Kang H, Kelleher A, Keppel C, Koirala S, Korover I, LeRose JJ, Lindgren R, Long E, Magne M, Mammei J, Margaziotis DJ, Markowitz P, Martí Jiménez-Argüello A, Meddi F, Meekins D, Michaels R, Mihovilovic M, Muangma N, Muñoz Camacho C, Nadel-Turonski P, Nuruzzaman N, Paremuzyan R, Puckett A, Punjabi V, Qiang Y, Rakhman A, Rashad MN, Riordan S, Roche J, Russo G, Sabatié F, Saenboonruang K, Saha A, Sawatzky B, Selvy L, Shahinyan A, Sirca S, Solvignon P, Sperduto ML, Subedi R, Sulkosky V, Sutera C, Tobias WA, Urciuoli GM, Wang D, Wojtsekhowski B, Yao H, Ye Z, Zana L, Zhan X, Zhang J, Zhao B, Zhao Z, Zheng X, and Zhu P

Abstract

We present deeply virtual π^{0} electroproduction cross-section measurements at x_{B}=0.36 and three different Q^{2} values ranging from 1.5 to 2  GeV^{2}, obtained from Jefferson Lab Hall A experiment E07-007. The Rosenbluth technique is used to separate the longitudinal and transverse responses. Results demonstrate that the cross section is dominated by its transverse component and, thus, is far from the asymptotic limit predicted by perturbative quantum chromodynamics. Nonetheless, an indication of a nonzero longitudinal contribution is provided by the measured interference term σ_{LT}. Results are compared with several models based on the leading-twist approach of generalized parton distributions (GPDs). In particular, a fair agreement is obtained with models in which the scattering amplitude includes convolution terms of chiral-odd (transversity) GPDs of the nucleon with the twist-3 pion distribution amplitude. This experiment, together with previous extensive unseparated measurements, provides strong support to the exciting idea that transversity GPDs can be accessed via neutral pion electroproduction in the high-Q^{2} regime.

Published
2016
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