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Title: Study of Double Spin Asymmetries in Inclusive ep Scattering at Jefferson Lab

The spin structure of the proton has been investigated in the high Bjorken x and low momentum transfer Q2 region. We used Jefferson Lab's polarized electron beam, a polarized target, and a spectrometer to get both the parallel and perpendicular spin asymmetries Apar and Aperp. These asymmetries produced the physics asymmetries A_1 and A_2 and spin structure functions g_1 and g_2. We found Q2 dependences of the asymmetries at resonance region and higher-twist effects. Our result increases the available data on the proton spin structure, especially at resonance region with low Q2. Moreover, A_2 and g_2 data show clear Q2 evolution, comparing with RSS and SANE-BETA. Negative resonance in A_2 data needs to be examined by theory. It can be an indication of very negative transverse-longitudinal interference contribution at W ~ 1.3 GeV. Higher twist effect appears at the low Q2 of 1.9 GeV2, although it is less significant than lower Q2 data of RSS. Twist03 matrix element d_2 was calculated using our asymmetry fits evaluation at Q2 – 1.9 GeV2. D-bar_2 = -0.0087±0.0014 was obtained by integrating 0.47 ≤ x ≤ 0.87.
  1. Seoul National Univ. (Korea, Republic of)
Publication Date:
OSTI Identifier:
Report Number(s):
JLAB-PHY--14-2001; DOE/OR/23177--3456
DOE Contract Number:
Resource Type:
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
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS double spin asymmetry; proton spin structure; operator product expansion; nucleon resonance; electron-proton scattering; Jefferson Lab