Beam-Target Helicity Asymmetry for gamma_pol n_pol in pi^- p n the N*Resonance Region

Ho, D.; Peng, P.; Bass, C.; Collins, P.; D'Angelo, A.; Deur, A.; Fleming, J.; Hanretty, C.; Kageya, T.; Khandaker, M.; Klein, F. J.; Klempt, E.; Laine, V.; Lowry, M. M.; Lu, H.; Nepali, C.; Nikonov, V. A.; O'Connell, T.; Sandorfi, A. M.; Sarantsev, A. V.; Schumacher, R. A.; Strakovsky, I. I.; Å&nbsp;varc, A.; Walford, N. K.; Wei, X.; Whisnant, C. S.; Workman, R. L.; Zonta, I.; Adhikari, K. P.; Adikaram, D.; Akbar, Z.; Amaryan, M. J.; Anefalos Pereira, S.; Avakian, H.; Ball, J.; Bashkanov, M.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Biselli, A.; Briscoe, W. J.; Burkert, V. D.; Carman, D. S.; Celentano, A.; Charles, G.; Chetry, T.; Ciullo, G.; Clark, L.; Colaneri, L.; Cole, P. L.; Contalbrigo, M.; Crede, V.; Dashyan, N.; De Sanctis, E.; De Vita, R.; Djalali, C.; Dupre, R.; El Alaoui, A.; El Fassi, L.; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Fersch, R.; Filippi, A.; Fradi, A.; Ghandilyan, Y.; Gilfoyle, G. P.; Girod, F. X.; Glazier, D. I.; Gleason, C.; Gohn, W.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guidal, M.; Guo, L.; Hakobyan, H.; Harrison, N.; Hattawy, M.; Hicks, K.; Holtrop, M.; Hughes, S. M.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jenkins, D.; Jiang, H.; H. S., Jo; Joo, K.; Joosten, S.; Keller, D.; Khachatryan, G.; Kim, A.; Kim, W.; Klein, A.; Kubarovsky, V.; Kuleshov, S. V.; Lanza, L.; Lenisa, P.; Livingston, K.; Macgregor, I. J. D.; Markov, N.; Mckinnon, B.; Mineeva, T.; Mokeev, V.; Montgomery, R. A.; Movsisyan, A.; Munoz Camacho, C.; Murdoch, G.; Niccolai, S.; Niculescu, G.; Osipenko, M.; Paolone, M.; Paremuzyan, R.; Park, K.; Pasyuk, E.; Phelps, W.; Pogorelko, O.; Price, J. W.; Procureur, S.; Protopopescu, D.; Ripani, M.; Riser, D.; Ritchie, B. G.; Rizzo, A.; Rosner, G.; Sabatiã©, F.; Salgado, C.; Sharabian, Y. G.; Skorodumina, Iu.; Smith, G. D.; Sober, D. I.; Sokhan, D.; Sparveris, N.; Strauch, S.; Tian, Ye; Torayev, B.; Ungaro, M.; Voskanyan, H.; Voutier, E.; Watts, D. P.; Wood, M. H.; Zachariou, N.; Zhang, J.; Zhao, Z. W.

doi:10.1103/PhysRevLett.118.242002

We report the first beam-target double-polarization asymmetries in the gamma + n(p) to pi^(-) + p(p) reaction spanning the nucleon resonance region from invariant mass W=1500 to 2300 MeV. Circularly polarized photons and longitudinally polarized deuterons in solid hydrogen deuteride (HD) have been used with the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. The exclusive final state has been extracted using three very different analyses that show excellent agreement, and these have been used to deduce the E polarization observable for an effective neutron target. These results have been incorporated into new partial wave analyses and have led to significant revisions for several gammanN* resonance photocouplings.