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

Thesis/Dissertation · Fri Aug 01 00:00:00 EDT 2014

DOI:https://doi.org/10.2172/1190863· OSTI ID:1190863

Kang, Hoyoung ^[1]

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1. Seoul National Univ. (Korea, Republic of)

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.

• Research Organization: Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• DOE Contract Number: AC05-06OR23177
• OSTI ID: 1190863
• Report Number(s): JLAB-PHY-14-2001; DOE/OR/23177-3456
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
double spin asymmetry
proton spin structure
operator product expansion
nucleon resonance
electron-proton scattering
Jefferson Lab