Measurement of ep→epπ0 beam spin asymmetries above the resonance region

R. De Masi, M. Garçon, B. Zhao, M. J. Amaryan, P. Ambrozewicz, M. Anghinolfi, G. Asryan, H. Avakian, H. Bagdasaryan, N. Baillie, J. Ball, J. P. Ball, N. A. Baltzell, V. Batourine, M. Battaglieri, I. Bedlinskiy, M. Bellis, N. Benmouna, B. L. Berman, P. BertinA. S. Biselli, L. Blaszczyk, S. Bouchigny, S. Boiarinov, R. Bradford, D. Branford, W. J. Briscoe, W. K. Brooks, S. Bültmann, V. D. Burkert, C. Butuceanu, J. R. Calarco, S. L. Careccia, D. S. Carman, L. Casey, S. Chen, L. Cheng, P. L. Cole, P. Collins, P. Coltharp, D. Crabb, V. Crede, N. Dashyan, E. De Sanctis, R. De Vita, P. V. Degtyarenko, A. Deur, K. V. Dharmawardane, R. Dickson, C. Djalali, G. E. Dodge, J. Donnelly, D. Doughty, Michael Dugger, O. P. Dzyubak, H. Egiyan, K. S. Egiyan, L. El Fassi, L. Elouadrhiri, P. Eugenio, G. Fedotov, G. Feldman, A. Fradi, H. Funsten, G. Gavalian, G. P. Gilfoyle, K. L. Giovanetti, F. X. Girod, J. T. Goetz, A. Gonenc, R. W. Gothe, K. A. Griffioen, M. Guidal, N. Guler, L. Guo, V. Gyurjyan, K. Hafidi, H. Hakobyan, C. Hanretty, F. W. Hersman, K. Hicks, I. Hleiqawi, M. Holtrop, C. E. Hyde-Wright, Y. Ilieva, D. G. Ireland, B. S. Ishkhanov, E. L. Isupov, M. M. Ito, D. Jenkins, H. S. Jo, J. R. Johnstone, K. Joo, H. G. Juengst, N. Kalantarians, J. D. Kellie, M. Khandaker, W. Kim, A. Klein, F. J. Klein, A. V. Klimenko, M. Kossov, Z. Krahn, L. H. Kramer, V. Kubarovsky, J. Kuhn, S. E. Kuhn, S. V. Kuleshov, J. Lachniet, J. M. Laget, J. Langheinrich, D. Lawrence, T. Lee, K. Livingston, H. Y. Lu, M. MacCormick, N. Markov, P. Mattione, M. Mazouz, B. McKinnon, B. A. Mecking, M. D. Mestayer, C. A. Meyer, T. Mibe, B. Michel, K. Mikhailov, M. Mirazita, R. Miskimen, V. Mokeev, B. Moreno, K. Moriya, S. A. Morrow, M. Moteabbed, E. Munevar, G. S. Mutchler, P. Nadel-Turonski, R. Nasseripour, S. Niccolai, G. Niculescu, I. Niculescu, B. B. Niczyporuk, M. R. Niroula, R. A. Niyazov, M. Nozar, M. Osipenko, A. I. Ostrovidov, K. Park, E. Pasyuk, C. Paterson, S. Anefalos Pereira, J. Pierce, N. Pivnyuk, D. Pocanic, O. Pogorelko, S. Pozdniakov, J. W. Price, S. Procureur, Y. Prok, D. Protopopescu, B. A. Raue, G. Ricco, M. Ripani, Barry Ritchie, F. Ronchetti, G. Rosner, P. Rossi, F. Sabatié, J. Salamanca, C. Salgado, J. P. Santoro, V. Sapunenko, R. A. Schumacher, V. S. Serov, Y. G. Sharabian, D. Sharov, N. V. Shvedunov, E. S. Smith, L. C. Smith, D. I. Sober, D. Sokhan, A. Stavinsky, S. Stepanyan, S. S. Stepanyan, B. E. Stokes, P. Stoler, I. I. Strakovsky, S. Strauch, M. Taiuti, D. J. Tedeschi, A. Tkabladze, S. Tkachenko, C. Tur, M. Ungaro, M. F. Vineyard, A. V. Vlassov, E. Voutier, D. P. Watts, L. B. Weinstein, D. P. Weygand, M. Williams, E. Wolin, M. H. Wood, A. Yegneswaran, L. Zana, J. Zhang, Z. W. Zhao

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Abstract

The beam spin asymmetry (BSA) in the exclusive reaction e→p→epπ0 was measured with the CEBAF 5.77 GeV polarized electron beam and Large Acceptance Spectrometer (CLAS). The xB,Q2,t, and dependences of the π0 BSA are presented in the deep inelastic regime. The asymmetries are fitted with a sin function and their amplitudes are extracted. Overall, they are of the order of 0.04-0.11 and roughly independent of t. This is the signature of a nonzero longitudinal-transverse interference. The implications concerning the applicability of a formalism based on generalized parton distributions, as well as the extension of a Regge formalism at high photon virtualities, are discussed.

Original languageEnglish (US)
Article number042201
JournalPhysical Review C - Nuclear Physics
Volume77
Issue number4
DOIs
StatePublished - Apr 14 2008

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

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    Masi, R. D., Garçon, M., Zhao, B., Amaryan, M. J., Ambrozewicz, P., Anghinolfi, M., Asryan, G., Avakian, H., Bagdasaryan, H., Baillie, N., Ball, J., Ball, J. P., Baltzell, N. A., Batourine, V., Battaglieri, M., Bedlinskiy, I., Bellis, M., Benmouna, N., Berman, B. L., ... Zhao, Z. W. (2008). Measurement of ep→epπ0 beam spin asymmetries above the resonance region. Physical Review C - Nuclear Physics, 77(4), [042201]. https://doi.org/10.1103/PhysRevC.77.042201