The Q^p_Weak experiment: A search for physics beyond the standard model via a measurement of the proton's weak charge

In May 2012, the Q^p_Weak collaboration completed a two year measurement program to determine the weak charge of the proton Q^p_Weak = (1 - 4 sin²θ_W at the Thomas Jefferson National Accelerator Facility (TJNAF). The experiment was designed to produce a 4. 0 % measurement of the weak charge, via a 2. 5 % measurement of the parity violating asymmetry in the number of elastically scattered 1. 165 GeV electrons from protons, at forward angles. At the proposed precision, the experiment would produce a 0. 3 % measurement of the weak mixing angle at a momentum transfer of Q² = 0. 026 GeV², making it the most precise stand alone measurement of the weak mixing angle at low momentum transfer. In combination with other parity measurements, Q^p_Weak will also provide a high precision determination of the weak charges of the up and down quarks. At the proposed precision, a significant deviation from the Standard Model prediction could be a signal of new physics at mass scales up to ≃ 6 TeV, whereas agreement would place new and significant constraints on possible Standard Model extensions at mass scales up to ≃ 2 TeV. This paper provides an overview of the physics and the experiment, as well as a brief look at some preliminary diagnostic and analysis data.