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Title: First measurement of the polarization observable E in the p(yπ+)n reaction up to 2.25 GeV

First results from the longitudinally polarized frozen-spin target (FROST) program are reported. The double-polarization observable E , for the reaction yp→π+n, has been measured using a circularly polarized tagged-photon beam, with energies from 0.35 to 2.37 GeV. The final-state pions were detected with the CEBAF Large Acceptance Spectrometer in Hall B at the Thomas Jefferson National Accelerator Facility. These polarization data agree fairly well with previous partial-wave analyses at low photon energies. Over much of the covered energy range, however, significant deviations are observed, particularly in the high-energy region where high-L multipoles contribute. The data have been included in new multipole analyses resulting in updated nucleon resonance parameters. Lastly, we report updated fits from the Bonn–Gatchina, Jülich–Bonn, and SAID groups.
Authors:
 [1]
  1. Univ. of South Carolina, Columbia, SC (United States). et al.
Publication Date:
Report Number(s):
JLAB-PHY-15-2025; DOE/OR/23177-3325; arXiv:1503.05163
Journal ID: ISSN 0370-2693; PII: S0370269315006541
Grant/Contract Number:
SFB/TR16; AC05-060R23177; AC05-06OR23177
Type:
Published Article
Journal Name:
Physics Letters. Section B
Additional Journal Information:
Journal Volume: 750; Journal Issue: C; Conference: Grindelwald (Switzlerland), 8-12 Oct 2010; Journal ID: ISSN 0370-2693
Publisher:
Elsevier
Research Org:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Jefferson Science Associates, LLC, Newport News, VA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
Contributing Orgs:
Jefferson Lab CLAS Collaboration; The CLAS Collaboration
Country of Publication:
United States
Language:
English
Subject:
Baryon spectroscopy; pion photoproduction; polarization observables; FROST experiment; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
OSTI Identifier:
1213897
Alternate Identifier(s):
OSTI ID: 1213680; OSTI ID: 1241245