Measurement of the generalized form factors near threshold via γ^{*}p→nπ^{+} at high Q^{2}

Park, K.; Gothe, R.; Adhikari, K.; Adikaram, D.; Anghinolfi, M.; Baghdasaryan, H.; Ball, J.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Bennett, R.; Biselli, A.; Bookwalter, C.; Boiarinov, S.; Branford, D.; Briscoe, W.; Brooks, W.; Burkert, V.; Carman, D.; Celentano, A.; Chandavar, S.; Charles, G.; Cole, P.; Contalbrigo, M.; Crede, V.; D'Angelo, A.; Daniel, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Doughty, D.; Dupre, R.; El Alaoui, A.; El Fassi, L.; Eugenio, P.; Fedotov, G.; Fradi, A.; Gabrielyan, M.; Gevorgyan, N.; Gilfoyle, G.; Giovanetti, K.; Girod, F.; Goetz, J.; Gohn, W.; Golovatch, E.; Graham, L.; Griffioen, K.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Heddle, D.; Hicks, K.; Holtrop, M.; Hyde, C.; Ilieva, Y.; Ireland, D.; Ishkhanov, B.; Isupov, E.; Jenkins, D.; Jo, H.; Joo, K.; Kalantarians, N.; Khandaker, M.; Khetarpal, P.; Kim, A.; Kim, W.; Klein, A.; Klein, F.; Kubarovsky, A.; Kubarovsky, V.; Kuhn, S.; Kuleshov, S.; Kvaltine, N.; Livingston, K.; Lu, H.; Macgregor, I.; Markov, N.; Mayer, M.; Mckinnon, B.; Mestayer, M.; Meyer, C.; Mineeva, T.; Mirazita, M.; Mokeev, V.; Moutarde, H.; Munevar, E.; Nadel Turonski, P.; Nasseripour, R.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Osipenko, M.; Ostrovidov, A.; Paolone, M.; Pappalardo, L.; Paremuzyan, R.; Park, S.; Anefalos Pereira, S.; Phelps, E.; Pisano, S.; Pogorelko, O.; Pozdniakov, S.; Price, J.; Procureur, S.; Prok, Y.; Ricco, Giovanni; Rimal, D.; Ripani, M.; Ritchie, B.; Rosner, G.; Rossi, P.; Sabatié, F.; Saini, M.; Salgado, C.; Schott, D.; Schumacher, R.; Seraydaryan, H.; Sharabian, Y.; Smith, E.; Smith, G.; Sober, D.; Sokhan, D.; Stepanyan, S.; Stepanyan, S.; Stoler, P.; Strakovsky, I.; Strauch, S.; Taiuti, MAURO GINO; Tang, W.; Taylor, C.; Tian, Y.; Tkachenko, S.; Trivedi, A.; Ungaro, M.; Vernarsky, B.; Vlassov, A.; Voutier, E.; Watts, D.; Weygand, D.; Wood, M.; Zachariou, N.; Zhao, B.; Zhao, Z.

doi:10.1103/PhysRevC.85.035208

We report the first extraction of the pion-nucleon multipoles near the production threshold for the nπ+ channel at relatively high momentum transfer (Q2 up to 4.2 GeV2). The dominance of the s-wave transverse multipole (E0+), expected in this region, allowed us to access the generalized form factor G1 within the light-cone sum-rule (LCSR) framework as well as the axial form factor GA. The data analyzed in this work were collected by the nearly 4π CEBAF Large Acceptance Spectrometer (CLAS) using a 5.754-GeV electron beam on a proton target. The differential cross section and the π-N multipole E0+/GD were measured using two different methods, the LCSR and a direct multipole fit. The results from the two methods are found to be consistent and almost Q2 independent.