Beam spin asymmetry measurements of deeply virtual π0 production with CLAS12

Kim, A.; Diehl, S.; Joo, K.; Kubarovsky, V.; Achenbach, P.; Akbar, Z.; Alvarado, J. S.; Armstrong, Whitney R.; Atac, H.; Avakian, H.; Ayerbe Gayoso, C.; Barion, L.; Battaglieri, M.; Bedlinskiy, I.; Benkel, B.; Bianconi, A.; Biselli, A. S.; Bondi, M.; Bossù, F.; Boiarinov, S.; Brinkmann, K. T.; Briscoe, W. J.; Brooks, W. K.; Bueltmann, S.; Burkert, V. D.; Capobianco, R.; Carman, D. S.; Carvajal, J. C.; Celentano, A.; Charles, G.; Chatagnon, P.; Chesnokov, V.; Chetry, T.; Ciullo, G.; Clary, B.; Clash, G.; Cole, P. L.; Contalbrigo, M.; Costantini, G.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; Defurne, M.; Deur, A.; Dilks, C.; Djalali, C.; Dupre, R.; Egiyan, H.; Ehrhart, M.; El Alaoui, A.; El Fassi, L.; Fegan, S.; Filippi, A.; Fogler, C.; Gavalian, G.; Gilfoyle, G. P.; Gosta, G.; Girod, F. X.; Glazier, D. I.; Golubenko, A. A.; Gothe, R. W.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hattawy, M.; Hauenstein, F.; Hayward, T. B.; Heddle, D.; Hobart, A.; Holtrop, M.; Hung, Yu-Chun; Ilieva, Y.; Ireland, D. G.; Isupov, E.; H. S., Jo; Johnston, R.; Joosten, S.; Khachatryan, M.; Khanal, A.; Kim, W.; Klimenko, V.; Kripko, A.; Kuhn, S. E.; Lanza, L.; Leali, M.; Kabir, M. L.; Lee, S.; Lenisa, P.; Li,; Macgregor, X. J. D.; Marchand, D.; Mascagna, V.; Mckinnon, B.; Matamoros, D.; Migliorati, S.; Mineeva, T.; Mirazita, M.; Mokeev, V.; Moran, P.; Munoz Camacho, C.; Naidoo, P.; Neupane, K.; Nguyen, D.; Niccolai, S.; Niculescu, G.; Osipenko, M.; Ouillon, M.; Pandey, P.; Paolone, M.; Pappalardo, L. L.; Paremuzyan, R.; Pasyuk, E.; Paul, S. J.; Phelps, W.; Pilleux, N.; Pokhrel, M.; Poudel, J.; Price, J. W.; Prok, Y.; Radic, A.; Ramasubramanian, N.; Reed, Trevor; Richards, J.; Ripani, M.; Ritman, J.; Rossi, P.; Sabatié, F.; Salgado, C.; Schadmand, S.; Schmidt, A.; Sharabian, Y. G.; Shirokov, E. V.; Shrestha, U.; Sokhan, D.; Sparveris, N.; Spreafico, M.; Stepanyan, S.; Strakovsky, I. I.; Strauch, S.; Tan, J.; Trotta, N.; Tyson, R.; Ungaro, M.; Vallarino, S.; Venturelli, L.; Voskanyan, H.; Voutier, E.; Watts, D. P.; Wei, X.; Wishart, R.; Wood, M. H.; Yurov, M.; Zachariou, N.; Zhang, J.; Ziegler, V.; Zurek, M.

doi:10.1016/j.physletb.2024.138459

The new experimental measurements of beam spin asymmetry were performed for the deeply virtual exclusive pi(0) production in a wide kinematic region with the photon virtualities Q(2) up to 6.6 GeV2 and the Bjorken scaling variable x(B) in the valence regime. The data were collected by the CEBAF Large Acceptance Spectrometer (CLAS12) at Jefferson Lab with longitudinally polarized 10.6 GeV electrons scattered on an unpolarized liquid-hydrogen target. Sizable asymmetry values indicate a substantial contribution from transverse virtual photon amplitudes to the polarized structure functions. The interpretation of these measurements in terms of the Generalized Parton Distributions (GPDs) demonstrates their sensitivity to the chiral-odd GPD (E) over bar (T), which contains information on quark transverse spin densities in unpolarized and polarized nucleons and provides access to the nucleon's transverse anomalous magnetic moment. Additionally, the data were compared to a theoretical model based on a Regge formalism that was extended to the high photon virtualities.