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Title: Target and beam-target spin asymmetries in exclusive pion electroproduction for Q 2 > 1 GeV 2 . II. e p e π 0 p

Beam-target double-spin asymmetries and target single-spin asymmetries were measured for the exclusive π + electroproduction reaction γ*p→nπ +. 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 range covered is 1.1 < W < 3 GeV and 1 < Q 2 < 6GeV 2. Results were obtained for about 6000 bins in W, Q 2, cos(θ*), and Φ*. Except at forward angles, very large target-spin asymmetries are observed over the entire W region. Reasonable agreement is found with phenomenological fits to previous data for W < 1.6 GeV, but very large differences are seen at higher values of W. A generalized parton distributions (GPD)-based model is in poor agreement with the data. As a result, when combined with cross-sectional measurements, the present results provide powerful constraints on nucleon resonance amplitudes at moderate and large values of Q 2, for resonances with masses as high as 2.4 GeV.
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Publication Date:
Report Number(s):
JLAB-PHY-16-2388; DOE/OR/23177-4014; arXiv:1611.04987
Journal ID: ISSN 2469-9985; PRVCAN; TRN: US1700598
Grant/Contract Number:
AC05-84ER40150; AC05-06OR23177; AC02-06CH11357; SC0016583
Type:
Accepted Manuscript
Journal Name:
Physical Review C
Additional Journal Information:
Journal Volume: 95; Journal Issue: 3; Journal ID: ISSN 2469-9985
Publisher:
American Physical Society (APS)
Research Org:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Argonne National Lab. (ANL), Argonne, IL (United States); George Washington Univ., Washington, DC (United States)
Sponsoring Org:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26); National Science Foundation (NSF); National Research Foundation of Korea (NRF); United Kingdom Science and Technology Facilities Council; Instituto Nazionale di Fisica Nucleare (INFN)
Contributing Orgs:
CLAS Collaboration
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
OSTI Identifier:
1348182
Alternate Identifier(s):
OSTI ID: 1347814; OSTI ID: 1373715; OSTI ID: 1439720