Recent Results in Parity-Violating Electron Scattering at Jefferson Lab: PREX and HAPPEX-III

Conference · Fri Apr 01 04:00:00 EDT 2011

OSTI ID:1970321

Paschke, Kent ^[1]

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1. Univ. of Virginia, Charlottesville, VA (United States)

The parity-violating asymmetry APV in electron scattering from the 208Pb nucleus is cleanly sensitive to the neutron radius Rn. A precision measurement of Rn would have important implications for the understanding of nuclear structure, and be a powerful constaint on the symmetry energy Sν(n) of neutron-rich nuclear matter, including neutron stars. The PREX collaboration has completed a first run, measuring Rn to a precision of ~2.5\%. The measurement of APV in electron-proton scattering is sensitive to vector form-factors associated with an intrinsic strange quark content of the nucleon. While at one time such contributions were considered to be potentially large, a world-wide program of parity-violation measurements has constrained these form-factors to be smaller than a few percent of the electric and magnetic form-factors of the proton at low momentum-transfer. HAPPEX-III has recently completed a measurement to improve the precision of this constaint at Q2~0.6GeV2, a region in which previous experiments had indicated the possibility of intriguingly large strange contributions. Results from each experiment, and prospects for more precise Rn measurements, will be discussed.

• Research Organization: Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• DOE Contract Number: AC05-06OR23177
• OSTI ID: 1970321
• Report Number(s): JLAB-PHY-11-1586; DOE/OR/23177-6073
• Country of Publication: United States
• Language: English