Deeply virtual Compton scattering off the neutron

Journal Article · 27 January 2020 · Nature Physics

DOI: https://doi.org/10.1038/s41567-019-0774-3 · OSTI ID:1603311

Benali, M. ; Desnault, C.; Mazouz, M.; Ahmed, Z.; Albataineh, H.; Allada, K.; Aniol, K. A.; Bellini, V.; Boeglin, W.; Bertin, P.; Brossard, M.; Camsonne, A.; Canan, M.; Chandavar, S.; Chen, C.; Chen, J. -P.; Defurne, M.; de Jager, C. W.; de Leo, R.; 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, G. M.; Hyde, C. E.; Iqbal, S.; Itard, F.; Kang, Ho.; Kang, Hy.; Kelleher, A.; Keppel, C.; Koirala, S.; Korover, I.; LeRose, J. J.; Lindgren, R.; Long, E. ; Magne, M.; Mammei, J.; Margaziotis, D. J.; 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.; Pomatsalyuk, R.; Puckett, A. ; Punjabi, V.; Qiang, Y.; Rakhman, A.; Rashad, M. N. H.; Riordan, S. ; Roche, J.; Russo, G.; Sabatié, F.; Saenboonruang, K.; Saha, A.; Sawatzky, B. ; Selvy, L.; Shahinyan, A.; Sirca, S.; Solvignon, P.; Sperduto, M. L.; Subedi, R.; Sulkosky, V.; Sutera, C.; Tobias, W. A.; Urciuoli, G. M.; Wang, D.; Wojtsekhowski, B. ; Yao, H. ; Ye, Z. ; Zana, L.; Zhan, X.; Zhang, J.; Zhao, B.; Zhao, Z.; Zheng, X.; Zhu, P.

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 quasifree 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. The internal structure of the neutron has now been probed by highly energetic photons scattering off it. Combined with previous results for protons, these measurements reveal the contributions of quark flavours to the nucleon structure.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
• Sponsoring Organization: National Science Foundation (NSF); Centre National de la Recherche Scientifique (CNRS); Commissariat a l’Energie Atomique (CEA); USDOE Office of Science (SC), Nuclear Physics (NP)
• Contributing Organization: The Jefferson Lab Hall A Collaboration; Hall A Collaboration
• Grant/Contract Number: AC02-06CH11357; AC05-06OR23177
• OSTI ID: 1603311
• Alternate ID(s): OSTI ID: 1639700
• Report Number(s): JLAB-PHY-20-3225; DOE-OR-23177-5005; 147594; TRN: US2104087
• Journal Information: Nature Physics, Vol. 16, Issue 2; ISSN 1745-2473
• Publisher: Nature Publishing Group (NPG)Copyright Statement
• Country of Publication: United States
• Language: English