Measurement of deeply virtual compton scattering beam-spin asymmetries
Doi:10.1103/PhysRevLett.87.182001 Copyright 2008 by The American Physical Society.
The beam-spin asymmetry in hard electroproduction of photons has been measured. The data have been accumulated by the HERMES experiment at DESY using the HERA 27.6 GeV longitudinally polarized positron beam and an unpolarized hydrogen-gas target. The asymmetry in the azimuthal distribution of the produced photons in the angle φ relative to the lepton scattering plane was determined with respect to the helicity state of the incoming positron beam. The beam-spin analyzing power in the sinφ moment was measured to be -0.23±0.04(stat)±0.03(syst) in the missing-mass range below 1.7 GeV. The observed asymmetry is attributed to the interference of the Bethe-Heitler and deeply virtual Compton scattering processes.
FX Girod, RA Niyazov, H Avakian, J Ball, I Bedlinskiy, VD Burkert, R De Masi, L Elouadrhiri, M Garcon, M Guidal, HS Jo, K Joo, V Kubarovsky, SV Kuleshov, M MacCormick, S Niccolai, O Pogorelko, F Sabatie, S Stepanyan, P Stoler, M Ungaro, B Zhao, MJ Amaryan, P Ambrozewicz, M Anghinolfi, G Asryan, H Bagdasaryan, N Baillie, JP Ball, NA Baltzell, V Batourine, M Battaglieri, M Bellis, N Benmouna, BL Berman, AS Biselli, L Blaszczyk, S Bouchigny, S Boiarinov, R Bradford, D Branford, WJ Briscoe, WK Brooks, S Bultmann, C Butuceanu, JR Calarco, SL Careccia, DS Carman, L Casey, S Chen, L Cheng, PL Cole, P Collins, P Coltharp, D Crabb, V Crede, N Dashyan, E De Sanctis, R De Vita, PV Degtyarenko, A Deur, KV Dharmawardane, R Dickson, C Djalali, GE Dodge, J Donnelly, D Doughty, M Dugger, OP Dzyubak, H Egiyan, KS Egiyan, L El Fassi, P Eugenio, G Fedotov, G Feldman, H Funsten, G Gavalian, GP Gilfoyle, KL Giovanetti, JT Goetz, A Gonenc, RW Gothe, KA Griffioen, N Guler, L Guo, V Gyurjyan, K Hafidi, H Hakobyan, C Hanretty, FW Hersman, K Hicks, I Hleiqawi, M Holtrop, CE Hyde, Y Ilieva, DG Ireland, BS Ishkhanov, EL Isupov, MM Ito, D Jenkins, JR Johnstone, HG Juengst, N Kalantarians, JD Kellie, M Khandaker, W Kim, A Klein, FJ Klein, AV Klimenko, M Kossov, Z Krahn, LH Kramer, J Kuhn, SE Kuhn, J Lachniet, JM Laget, J Langheinrich, D Lawrence, T Lee, K Livingston, HY Lu, N Markov, P Mattione, M Mazouz, B McKinnon, BA Mecking, MD Mestayer, CA Meyer, T Mibe, B Michel, K Mikhailov, M Mirazita, R Miskimen, V Mokeev, K Moriya, SA Morrow, M Moteabbed, E Munevar, GS Mutchler, P Nadel-Turonski, R Nasseripour, G Niculescu, I Niculescu, BB Niczyporuk, MR Niroula, M Nozar, M Osipenko, AI Ostrovidov, K Park, E Pasyuk, C Paterson, SA Pereira, J Pierce, N Pivnyuk, D Pocanic, S Pozdniakov, JW Price, S Procureur, Y Prok, D Protopopescu, BA Raue, G Ricco, M Ripani, BG Ritchie, G Rosner, P Rossi, J Salamanca, C Salgado, JP Santoro, V Sapunenko, RA Schumacher, VS Serov, YG Sharabian, D Sharov, NV Shvedunov, ES Smith, LC Smith, DI Sober, D Sokhan, A Stavinsky, SS Stepanyan, BE Stokes, II Strakovsky, S Strauch, M Taiuti, DJ Tedeschi, A Tkabladze, S Tkachenko, C Tur, MF Vineyard, AV Vlassov, E Voutier, DP Watts, LB Weinstein, DP Weygand, M Williams, E Wolin, MH Wood, A Yegneswaran, L Zana, J Zhang, and ZW Zhao. "Measurement of deeply virtual compton scattering beam-spin asymmetries" Physical Review Letters 100.16 (2008).
Available at: http://works.bepress.com/michael_williams/54