Target and Beam-Target Spin Asymmetries in Exclusive Pion Electroproduction for Q² > 1 GeV² . II. ep→ eπºp

Authors

CLAS Collaboration
K. P. Adhikari, Old Dominion University
D. Adikaram, Old Dominion University
M. J. Amaryan, Old Dominion UniversityFollow
S. Bültmann, Old Dominion UniversityFollow
N. Guler, Old Dominion University
S E. KuhnFollow
A. Klein, Old Dominion UniversityFollow
S. Koirala, Old Dominion University
B. Torayev, Old Dominion UniversityFollow
J. Zhang, Old Dominion University
Z. W. Zhao, Old Dominion University

Document Type

Article

Publication Date

2017

DOI

10.1103/PhysRevC.95.035207

Publication Title

Physical Review C

Volume

95

Issue

3

Pages

035207 (12 pages)

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.

Comments

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Original Publication Citation

CLAS Collaboration, Bosted, P. E., Kim, A., Adhikari, K. P., Adikaram, D., Akbar, Z., . . . Zonta, I. (2017). Target and beam-target spin asymmetries in exclusive pion electroproduction for Q² > 1 GeV². II. Ep→ eπºp. Physical Review C, 95(3), 035207. doi:10.1103/PhysRevC.95.035207

ORCID

0000-0003-2243-6836 (Kuhn)

Repository Citation

CLAS Collaboration; Adhikari, K. P.; Adikaram, D.; Amaryan, M. J.; Bültmann, S.; Guler, N.; Kuhn, S E.; Klein, A.; Koirala, S.; Torayev, B.; Zhang, J.; and Zhao, Z. W., "Target and Beam-Target Spin Asymmetries in Exclusive Pion Electroproduction for Q² > 1 GeV² . II. ep→ eπºp" (2017). Physics Faculty Publications. 228.
https://digitalcommons.odu.edu/physics_fac_pubs/228