Qweak experiment update and applications/opportunities at lower energies

Abstract

The Qweak experiment has recently completed data-taking at Jefferson Lab. The primary focus of the experiment is to perform a precision measurement of the proton's neutral weak charge. The Standard Model gives a definite prediction for the weak charge. Any deviation from that can be interpreted as evidence for new physics beyond the Standard Model. This precision, low energy measurement is sensitive to new physics signatures at energy scales up to 2 TeV. The experiment measures the parity-violating asymmetry in the scattering of 1.165 GeV longitudinally polarized electrons on the proton at low momentum transfer (Q2 ∼ 0.025 (GeV/c)2). This paper provides a brief status report on the experiment with a focus on instrumentation and techniques that are applicable to lower beam energy realizations of parity-violating electron scattering measurements. Estimates of anticipated errors on the proton's weak charge expected if the Qweak apparatus were used at a lower beam energy are also discussed.