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Target and beam-target spin asymmetries in exclusive pion electroproduction for Q2>1 GeV2. II. ep→eπ0p TARGET and BEAM-TARGET SPIN .... II. ... P. E. BOSTED et al.
Journal
Physical Review C
Date Issued
2017-03-20
Author(s)
Bosted, P. E.
Kim, A.
Adhikari, K. P.
Adikaram, D.
Akbar, Z.
Amaryan, M. J.
Anefalos Pereira, S.
Avakian, H.
Badui, R. A.
Ball, J.
Balossino, I.
Battaglieri, M.
Bedlinskiy, I.
Biselli, A. S.
Boiarinov, S.
Briscoe, W. J.
Bültmann, S.
Burkert, V. D.
Cao, T.
Carman, D. S.
Celentano, A.
Chandavar, S.
Charles, G.
Chetry, T.
Ciullo, G.
Clark, L.
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.
Dupre, R.
Egiyan, H.
El Fassi, L.
Elouadrhiri, L.
Eugenio, P.
Fanchini, E.
Fedotov, G.
Fegan, S.
Fersch, R.
Filippi, A.
Fleming, J. A.
Forest, T. A.
Fradi, A.
Ghandilyan, Y.
Gilfoyle, G. P.
Girod, F. X.
Glazier, D. I.
Gohn, W.
Golovatch, E.
Gothe, R. W.
Griffioen, K. A.
Guidal, M.
Guler, N.
Guo, L.
Hafidi, K.
Hanretty, C.
Harrison, N.
Hattawy, M.
Heddle, D.
Hicks, K.
Hollis, G.
Holtrop, M.
Hughes, S. M.
Ireland, D. G.
Isupov, E. L.
Jenkins, D.
Jiang, H.
Jo, H. S.
Joo, K.
Keller, D.
Khachatryan, G.
Khandaker, M.
Kim, W.
Klei, A.
Klein, F. J.
Koirala, S.
Kubarovsky, V.
Kuhn, S. E.
Lanza, L.
Lenisa, P.
Livingston, K.
Lu, H. Y.
Macgregor, I. J.D.
Markov, N.
Mayer, M.
McCracken, M. E.
McKinnon, B.
Mirazita, M.
Mokeev, V. I.
Abstract
Beam-target double-spin asymmetries and target single-spin asymmetries were measured for the exclusive
π0 electroproduction reaction γ ∗p → pπ0, expanding an analysis of the γ ∗p → nπ+ reaction from the
same experiment. The results were obtained from scattering of 6-GeV longitudinally polarized electrons off
longitudinally polarized protons using the CEBAF Large Acceptance Spectrometer at Jefferson Laboratory. The
kinematic ranges covered are 1.1 <W< 3 GeV and 1 < Q2 < 6 GeV2
. Results were obtained for about 5700
bins in W, Q2, cos(θ ∗), and φ∗. The beam-target asymmetries were found to generally be greater than zero, with
relatively modest φ∗ dependence. The target asymmetries exhibit very strong φ∗ dependence, with a change in
sign occurring between results at low W and high W, in contrast to π+ electroproduction. Reasonable agreement
is found with phenomenological fits to previous data for W < 1.6 GeV, but significant differences are seen at
higher W. When combined with cross-sectional measurements, as well as π+ observables, the present results will
provide powerful constraints on nucleon resonance amplitudes at moderate and large values of Q2, for resonances
with masses as high as 2.4 GeV
π0 electroproduction reaction γ ∗p → pπ0, expanding an analysis of the γ ∗p → nπ+ reaction from the
same experiment. The results were obtained from scattering of 6-GeV longitudinally polarized electrons off
longitudinally polarized protons using the CEBAF Large Acceptance Spectrometer at Jefferson Laboratory. The
kinematic ranges covered are 1.1 <W< 3 GeV and 1 < Q2 < 6 GeV2
. Results were obtained for about 5700
bins in W, Q2, cos(θ ∗), and φ∗. The beam-target asymmetries were found to generally be greater than zero, with
relatively modest φ∗ dependence. The target asymmetries exhibit very strong φ∗ dependence, with a change in
sign occurring between results at low W and high W, in contrast to π+ electroproduction. Reasonable agreement
is found with phenomenological fits to previous data for W < 1.6 GeV, but significant differences are seen at
higher W. When combined with cross-sectional measurements, as well as π+ observables, the present results will
provide powerful constraints on nucleon resonance amplitudes at moderate and large values of Q2, for resonances
with masses as high as 2.4 GeV
Subjects
