Measurements of ep→e′π+nat1.6 Park, K.;Aznauryan, I. G.;Burkert, V. D.;Adhikari, K. P.;Amaryan, M. J.;Pereira, S. Anefalos;Avakian, H.;Battaglieri, M.;Badui, R.;Bedlinskiy, I.;Biselli, A. S.;Bono, J.;Briscoe, W. J.;Brooks, W. K.;Carman, D. S.;Celentano, A.;Chandavar, S.;Charles, G.;Colaneri, L.;Cole, P. L.;Contalbrigo, M.;Cortes, O.;Crede, V.;D'Angelo, A.;Dashyan, N.;De Vita, R.;De Sanctis, E.;Deur, A.;Djalali, C.;Doughty, D.;Dupre, R.;Egiyan, H.;Alaoui, A. El;Elouadrhiri, L.;Fassi, L. El;Eugenio, P.;Fedotov, G.;Fegan, S.;Fersch, R.;Filippi, A.;Fleming, J. A.;Garillon, B.;Garçon, M.;Gevorgyan, N.;Gilfoyle, G. P.;Giovanetti, K. L.;Girod, F. X.;Joo, H. S.;Goetz, J. T.;Golovatch, E.;Gothe, R. W.;Griffioen, K. A.;Guegan, B.;Guidal, M.;Guo, L.;Hakobyan, H.;Hanretty, C.;Hattawy, M.;Hicks, K.;Holtrop, M.;Hughes, S. M.;Hyde, C. E.;Ilieva, Y.;Ireland, D. G.;Ishkhanov, B. S.;Isupov, E. L.;Jenkins, D.;Jiang, H.;Jo, H. S.;Joo, K.;Joosten, S.;Keller, D.;Khandaker, M.;Kim, A.;Kim, W.;Klein, A.;Klein, F. J.;Kubarovsky, V.;Kuhn, S. E.;Kuleshov, S. V.;Lenisa, P.;Livingston, K.;Lu, H. Y.;MacGregor, I. J. D.;Markov, N.;Martinez, D.;McKinnon, B.;Mokeev, V.;Montgomery, R. A.;Moutarde, H.;Camacho, C. Munoz;Nadel-Turonski, P.;Niccolai, S.;Niculescu, G.;Niculescu, I.;Osipenko, M.;Ostrovidov, A. I.;Paolone, M.;Pasyuk, E.;Peng, P.;Phelps, W.;Phillips, J. J.;Pisano, S.;Pogorelko, O.;Price, J. W.;Procureur, S.;Prok, Y.;Protopopescu, D.;Puckett, A. J. R.;Raue, B. A.;Ripani, M.;Rizzo, A.;Rosner, G.;Rossi, P.;Roy, P.;Sabatié, F.;Salgado, C.;Schott, D.;Schumacher, R. A.;Seder, E.;Sharabian, Y. G.;Simonyan, A.;Skorodumina, Iu.;Smith, E. S.;Smith, G. D.;Sparveris, N.;Stoler, P.;Strakovsky, I. I.;Strauch, S.;Sytnik, V.;Taiuti, M.;Tang, W.;Taylor, C. E.;Tian, Ye;Trivedi, A.;Ungaro, M.;Voskanyan, H.;Voutier, E.;Walford, N. K.;Watts, D. P.;Wei, X.;Weinstein, L. B.;Wood, M. H.;Zachariou, N.;Zana, L.;Zhang, J.;Zhao, Z. W.;Zonta, I. 2015-04-13 Abstract Differential cross sections of the exclusive process ep -> e 'pi(+)n were measured with good precision in the range of the photon virtuality Q(2) = 1.8-4.5 GeV2 and the invariant mass range of the pi(+)n final state W = 1.6-2.0 GeV using the Continuous Electron Beam Accelerator Facility Large Acceptance Spectrometer. Data were collected with nearly complete coverage in the azimuthal and polar angles of the n pi(+) center-of-mass system. More than 37 000 cross-section points were measured. The contributions of the isospin I = 1/2 resonances N(1675) 5/2(-), N(1680) 5/2(+), and N(1710) 1/2(+) were extracted at different values of Q(2) using a single-channel, energy-dependent resonance amplitude analysis. Two different approaches, the unitary isobar model and the fixed-t dispersion relations, were employed in the analysis. We observe significant strength of the N(1675)5/2(-) in the A(1/2) amplitude, which is in strong disagreement with quark models that predict both transverse amplitudes to be strongly suppressed. For the N(1680)5/2(+) we observe a slow changeover from the dominance of the A(3/2) amplitude at the real photon point (Q(2) = 0) to a Q(2) where A(1/2) begins to dominate. The scalar amplitude S-1/2 drops rapidly with Q(2) consistent with quark model prediction. For the N(1710)1/2(+) resonance our analysis shows significant strength for the A1/2 amplitude at Q(2) < 2.5 GeV2.

Differential cross sections of the exclusive process ep -> e 'pi(+)n were measured with good precision in the range of the photon virtuality Q(2) = 1.8-4.5 GeV2 and the invariant mass range of the pi(+)n final state W = 1.6-2.0 GeV using the Continuous Electron Beam Accelerator Facility Large Acceptance Spectrometer. Data were collected with nearly complete coverage in the azimuthal and polar angles of the n pi(+) center-of-mass system. More than 37 000 cross-section points were measured. The contributions of the isospin I = 1/2 resonances N(1675) 5/2(-), N(1680) 5/2(+), and N(1710) 1/2(+) were extracted at different values of Q(2) using a single-channel, energy-dependent resonance amplitude analysis. Two different approaches, the unitary isobar model and the fixed-t dispersion relations, were employed in the analysis. We observe significant strength of the N(1675)5/2(-) in the A(1/2) amplitude, which is in strong disagreement with quark models that predict both transverse amplitudes to be strongly suppressed. For the N(1680)5/2(+) we observe a slow changeover from the dominance of the A(3/2) amplitude at the real photon point (Q(2) = 0) to a Q(2) where A(1/2) begins to dominate. The scalar amplitude S-1/2 drops rapidly with Q(2) consistent with quark model prediction. For the N(1710)1/2(+) resonance our analysis shows significant strength for the A1/2 amplitude at Q(2) < 2.5 GeV2.