Qweak: First Direct Measurement of the Weak Charge of the Proton

Conference · Tue Apr 01 00:00:00 EDT 2014 · EPJ Web of Conferences

DOI:https://doi.org/10.1051/epjconf/20147100100· OSTI ID:1168657

Nuruzzaman, NFN ^[1]

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1. Hampton University, JLAB

The Qweak experiment at Hall C of Thomas Jefferson National Accelerator Facility has made the first direct measurement of the weak charge of the proton, QWp, through a precision measurement of the parity-violating asymmetry in elastic e-p scattering at low momentum transfer Q2= 0.025 (GeV/c)2 with incident electron beam energy of 1.155 GeV. The Qweak experiment, along with earlier results of parity violating elastic scattering experiments, is expected to determine the most precise value of QWp which is suppressed in the Standard Model. If this result is further combined with the 133Cs atomic parity violation (APV) measurement, significant constraints on the weak charge of the up quark, down quark, and neutron can be extracted. This data will also be used to determine the weak-mixing angle, sin2 θW, with a relative uncertainty of < 0.5% that will provide a competitive measurement of the running of sin2 θW to low Q2. An overview of the experiment and its results using the commissioning dataset, constituting approximately 4% of the data collected in the experiment, are reported here.

• 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: 1168657
• Report Number(s): JLAB-PHY-13-1846; DOE/OR/23177-3073; arXiv:1312.6009
• Journal Information: EPJ Web of Conferences, Vol. 71; Conference: 2nd International Conference on New Frontiers in Physics, 28 August - 5 September 2013, Kolymbari, Crete, Greece
• Country of Publication: United States
• Language: English