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Title: Measurement of the generalized form factors near threshold via γ*p → nπ+ at high Q2

We report the first extraction of the pion-nucleon multipoles near the production threshold for the nπ+ channel at relatively high momentum transfer (Q2 up to 4.2 GeV2). The dominance of the s-wave transverse multipole (E0+), expected in this region, allowed us to access the generalized form factor G1 within the light-cone sum rule (LCSR) framework as well as the axial form factor GA. The data analyzed in this work were collected by the nearly 4π CEBAF Large Acceptance Spectrometer (CLAS) using a 5.754-GeV electron beam on a proton target. The differential cross section and the π-N multipole E0+/GD were measured using two different methods, the LCSR and a direct multipole fit. The results from the two methods are found to be consistent and almost Q2 independent.
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Publication Date:
OSTI Identifier:
1040720
Report Number(s):
JLAB-PHY--12-1412; DOE/OR/23177--1959; arXiv:1201.0903
Journal ID: ISSN 0556-2813; PRVCAN; TRN: US1202538
Grant/Contract Number:
AC05-06OR23177
Type:
Accepted Manuscript
Journal Name:
Physical Review. C, Nuclear Physics
Additional Journal Information:
Journal Volume: 85; Journal Issue: 3; Related Information: JLAB Experiment Number: E99-107; Journal ID: ISSN 0556-2813
Publisher:
American Physical Society (APS)
Research Org:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; DIFFERENTIAL CROSS SECTIONS; ELECTRON BEAMS; FORM FACTORS; LIGHT CONE; MOMENTUM TRANSFER; MULTIPOLES; PRODUCTION; PROTONS; SPECTROMETERS; SUM RULES