Target and beam-target spin asymmetries in exclusive pion electroproduction for Q2>1 GeV2. II. ep→eπ0p

Bosted, P; Kim, A; Adhikari, K; Adikaram, D; Akbar, Z; Amaryan, M; Anefalos Pereira, S; Avakian, H; Badui, R; Ball, J; Balossino, I; Battaglieri, M; Bedlinskiy, I; Biselli, A; Boiarinov, S; Briscoe, W; Brooks, W; Bultmann, S; Burkert, V; Cao, T; Carman, D; Celentano, A; Chandavar, S; Charles, G; Chetry, T; Ciullo, G; Clark, L; Colaneri, L; Cole, P; Contalbrigo, M; Cortes, O; Crede, V; D'Angelo, A; Dashyan, N; De Vita, R; De Sanctis, E; Deur, A; Djalali, C; Dupre, R; Egiyan, H; El Alaoui, A; El Fassi, L; Elouadrhiri, L; Eugenio, P; Fanchini, E; Fedotov, G; Fegan, S; Fersch, R; Filippi, A; Fleming, J; Forest, T; Fradi, A; Ghandilyan, Y; Gilfoyle, G; Girod, F; Glazier, D; Gohn, W; Golovatch, E; Gothe, R; Griffioen, K; Guidal, M; Guler, N; Hakobyan, H; Guo, L; Hafidi, K; Hakobyan, H; Hanretty, C; Harrison, N; Hattawy, M; Heddle, D; Hicks, K; Hollis, G; Holtrop, M; Hughes, S; Ireland, D; Isupov, E; Jenkins, D; Jiang, H; Hs, J; Joo, K; Keller, D; Khachatryan, G; Khandaker, M; Kim, W; Klei, A; Klein, F; Koirala, S; Kubarovsky, V; Kuhn, S; Lanza, L; Lenisa, P; Livingston, K; Hy, L; Macgregor, I; Markov, N; Mayer, M; Mccracken, M; Mckinnon, B; Mineeva, T; Mirazita, M; Mokeev, V; Montgomery, R; Movsisyan, A; Munoz Camacho, C; Murdoch, G; Nadel Turonski, P; Ni, A; Niccolai, S; Niculescu, G; Osipenko, M; Ostrovidov, A; Paolone, M; Paremuzyan, R; Park, K; Pasyuk, E; Phelps, W; Pisano, S; Pogorelko, O; Price, J; Prok, Y; Protopopescu, D; Puckett, A; Raue, B; Ripani, M; Rizzo, A; Rosner, G; Rossi, P; Roy, P; Sabatie, F; Saini, M; Schumacher, R; Seder, E; Sharabian, Y; Skorodumina, I; Smith, G; Sokhan, D; Sparveris, N; Stankovic, I; Stepanyan, S; Stoler, P; Strakovsky, I; Strauch, S; Taiuti, M; Tian, Y; Torayev, B; Ungaro, M; Voskanyan, H; Voutier, E; Walford, N; Watts, D; Wei, X; Weinstein, L; Zachariou, N; Zhang, J; Zhao, Z; Zonta, I

doi:10.1103/PhysRevC.95.035207

Beam-target double-spin asymmetries and target single-spin asymmetries were measured for the exclusive pi(0) electroproduction reaction. gamma(*) p -> p pi(0), expanding an analysis of the. gamma(*) p -> n pi(+) 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 GeV2. Results were obtained for about 5700 bins in W, Q(2), cos(theta(*)), and phi(*). The beam-target asymmetries were found to generally be greater than zero, with relatively modest phi(*) dependence. The target asymmetries exhibit very strong phi(*) dependence, with a change in sign occurring between results at low W and high W, in contrast to pi(+) electroproduction. Reasonable agreement is found with phenomenological fits to previous data for W < 1.6 GeV, but significant differences are seen at higherW. When combined with cross-sectional measurements, as well as pi(+) 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.

Bosted, P., Kim, A., Adhikari, K., Adikaram, D., Akbar, Z., Amaryan, M., et al. (2017). Target and beam-target spin asymmetries in exclusive pion electroproduction for Q2>1 GeV2. II. ep→eπ0p. PHYSICAL REVIEW C, 95(3), 1-12 [10.1103/PhysRevC.95.035207].