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This content will become publicly available on December 26, 2018

Title: Beam normal spin asymmetry for the e p e Δ ( 1232 ) process

Here, we calculate the single spin asymmetry for the $$e p \to e \Delta(1232)$$ process, for an electron beam polarized normal to the scattering plane. Such single spin asymmetries vanish in the one-photon exchange approximation, and are directly proportional to the absorptive part of a two-photon exchange amplitude. As the intermediate state in such two-photon exchange process is on its mass shell, the asymmetry allows one to access for the first time the on-shell $$\Delta \to \Delta$$ as well as $$N^\ast \to \Delta$$ electromagnetic transitions. We present the general formalism to describe the $$e p \to e \Delta$$ beam normal spin asymmetry, and provide a numerical estimate of its value using the nucleon, $$\Delta(1232)$$, $$S_{11}(1535)$$, and $$D_{13}(1520)$$ intermediate states. We compare our results with the first data from the Qweak@JLab experiment and give predictions for the A4@MAMI experiment.
Authors:
 [1] ;  [2] ;  [3] ;  [4]
  1. College of William and Mary, Williamsburg, VA (United States)
  2. Univ. degli Studie di Pavia, Pavia (Italy); INFN Sezione di Pavia, Pavia (Italy)
  3. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
  4. Johannes Gutenberg Univ., Mainz (Germany)
Publication Date:
Report Number(s):
JLAB-THY-17-2630; DOE/OR/23177-4301; arXiv:1708.05316
Journal ID: ISSN 2470-0010; PRVDAQ; TRN: US1800882
Grant/Contract Number:
PHY-1516509; AC05-06OR23177; FG02-87ER40365
Type:
Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 96; Journal Issue: 11; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society (APS)
Research Org:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
OSTI Identifier:
1416140
Alternate Identifier(s):
OSTI ID: 1414850