We report the first extraction of the pion-nucleon multipoles near the production threshold for the nπ+ channel at relatively high momentum transfer (Q2 up to 4.2 GeV2). The dominance of the s-wave transverse multipole (E0+), expected in this region, allowed us to access the generalized form factor G1 within the light-cone sum-rule (LCSR) framework as well as the axial form factor GA. The data analyzed in this work were collected by the nearly 4π CEBAF Large Acceptance Spectrometer (CLAS) using a 5.754-GeV electron beam on a proton target. The differential cross section and the π-N multipole E0+/GD were measured using two different methods, the LCSR and a direct multipole fit. The results from the two methods are found to be consistent and almost Q2 independent.
Copyright © 2012 American Physical Society. This article first appeared in Physical Review C 85, no. 3 (March 2012): 035208-1-35208-15. doi:10.1103/PhysRevC.85.035208.
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Park, K., R. W. Gothe, K. P. Adhikari, D. Adikaram, M. Anghinolfi, H. Baghdasaryan, J. Ball, M. Battaglieri, V. Batourine, I. Bedlinskiy, R. P. Bennett, A. S. Biselli, C. Bookwalter, S. Boiarinov, D. Branford, W. J. Briscoe, W. K. Brooks, V. D. Burkert, D. S. Carman, A. Celentano, S. Chandavar, G. Charles, P. L. Cole, M. Contalbrigo, V. Crede, A. D'Angelo, A. Daniel, N. Dashyan, R. De Vita, E. De Sanctis, A. Deur, C. Djalali, D. Doughty, R. Dupre, A. El Alaoui, L. El Fassi, P. Eugenio, G. Fedotov, A. Fradi, M. Y. Gabrielyan, N. Gevorgyan, G. P. Gilfoyle, K. L. Giovanetti, F. X. Girod, J. T. Goetz, W. Gohn, E. Golovatch, L. Graham, K. A. Griffioen, M. Guidal, L. Guo, K. Hafidi, H. Hakobyan, C. Hanretty, D. Heddle, K. Hicks, M. Holtrop, C. E. Hyde, Y. Ilieva, D. G. Ireland, B. S. Ishkhanov, E. L. Isupov, D. Jenkins, H. S. Jo, K. Joo, N. Kalantarians, M. Khandaker, P. Khetarpal, A. Kim, W. Kim, A. Klein, F. J. Klein, A. Kubarovsky, V. Kubarovsky, S. E. Kuhn, S. V. Kuleshov, N. D. Kvaltine, K. Livingston, H. Y. Lu, I. J. D. MacGregor, N. Markov, M. Mayer, B. McKinnon, M. D. Mestayer, C. A. Meyer, T. Mineeva, M. Mirazita, V. Mokeev, H. Moutarde, E. Munevar, P. Nadel-Turonski, R. Nasseripour, S. Niccolai, G. Niculescu, I. Niculescu, M. Osipenko, A. I. Ostrovidov, M. Paolone, L. Pappalardo, R. Paremuzyan, S. Park, S. Anefalos Pereira, E. Phelps, S. Pisano, O. Pogorelko, S. Pozdniakov, J. W. Price, S. Procureur, Y. Prok, G. Ricco, D. Rimal, M. Ripani, B. G. Ritchie, G. Rosner, P. Rossi, F. Sabatié, M. S. Saini, C. Salgado, D. Schott, R. A. Schumacher, H. Seraydaryan, Y. G. Sharabian, E. S. Smith, G. D. Smith, D. I. Sober, D. Sokhan, S. S. Stepanyan, S. Stepanyan, P. Stoler, I. I. Strakovsky, S. Strauch, M. Taiuti, W. Tang, C. E. Taylor, Y. Tian, S. Tkachenko, A. Trivedi, M. Ungaro, B. Vernarsky, A. V. Vlassov, E. Voutier, D. P. Watts, D. P. Weygand, M. H. Wood, N. Zachariou, B. Zhao, and Z. W. Zhao. "Measurement of the Generalized Form Factors Near Threshold via γ*p→nπ+ at High Q2." Physical Review C 85, no. 3 (March 2012): 035208:1-15. doi:10.1103/PhysRevC.85.035208.