Precise measurements of beam spin asymmetries in semi-inclusive pi(0) production

Aghasyan, M; Avakian, H; Rossi, P; De Sanctis, E; Hasch, D; Mirazita, M; Adikaram, D; Amaryan, M; Anghinolfi, M; Baghdasaryan, H; Ball, J; Battaglieri, M; Batourine, V; Bedlinskiy, I; Bennett, R; Biselli, A; Branford, D; Briscoe, W; Bultmann, S; Burkert, V; Carman, D; Chandavar, S; Cole, P; Collins, P; Contalbrigo, M; Crede, V; D'Angelo, Annalisa; Daniel, A; Dashyan, N; De Vita, R; Deur, A; Dey, B; Dickson, R; Djalali, C; Dodge, G; Doughty, D; Dupre, R; Egiyan, H; El Alaoui, A; Elouadrhiri, L; Eugenio, P; Fedotov, G; Fegan, S; Fradi, A; Gabrielyan, M; Garcon, M; Gevorgyan, N; Gilfoyle, G; Giovanetti, K; Girod, F; Goetz, J; Gohn, W; Golovatch, E; Gothe, R; Graham, L; Griffioen, K; Guegan, B; Guidal, M; Guler, N; Guo, L; Hafidi, K; Hanretty, C; Hicks, K; Holtrop, M; Hyde, C; Ilieva, Y; Ireland, D; Isupov, E; Jawalkar, S; Jenkins, D; Jo, H; Joo, K; Keller, D; Khandaker, M; Khetarpal, P; Kim, A; Kim, W; Klein, A; Klein, F; Kubarovsky, V; Kuhn, S; Kuleshov, S; Kuznetsov, V; Kvaltine, N; Livingston, K; Lu, H; Macgregor, I; Markov, N; Mayer, M; Mcandrew, J; Mckinnon, B; Meyer, C; Micherdzinska, A; Mokeev, V; Moreno, B; Moutarde, H; Munevar, E; Nadel Turonski, P; Ni, A; Niccolai, S; Niculescu, G; Niculescu, I; Osipenko, M; Ostrovidov, A; Paolone, M; Pappalardo, L; Paremuzyan, R; Park, K; Park, S; Pasyuk, E; Pereira, S; Phelps, E; Pisano, Silvia; Pogorelko, O; Pozdniakov, S; Price, J; Procureur, S; Prok, Y; Protopopescu, D; Raue, B; Ricco, G; Rimal, D; Ripani, M; Rosner, G; Sabatie, F; Saini, M; Salgado, C; Schott, D; Schumacher, R; Seder, E; Seraydaryan, H; Sharabian, Y; Smith, G; Sober, D; Stepanyan, S; Stepanyan, S; Stoler, P; Strakovsky, I; Strauch, S; Taiuti, M; Tang, W; Taylor, C; Tkachenko, S; Ungaro, M; Voskanyan, H; Voutier, E; Watts, D; Weinstein, L; Weygand, D; Wood, M; Zana, L; Zhang, J; Zhao, B; Zhao, Z.

doi:10.1016/j.physletb.2011.09.044

We present studies of single-spin asymmetries for neutral pion electroproduction in semi-inclusive deep-inelastic scattering of 5.776 GeV polarized electrons from an unpolarized hydrogen target, using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. A substantial sin phi(h) amplitude has been measured in the distribution of the cross section asymmetry as a function of the azimuthal angle phi(h) of the produced neutral pion. The dependence of this amplitude on Bjorken x and on the pion transverse momentum is extracted with significantly higher precision than previous data and is compared to model calculations.