The Proton's Weak Charge

Dr. David Armstrong

College of William and Mary

The Proton's Weak Charge

One of the highest priorities of present-day experimental particle and nuclear physics is to search for indications of physics which is not contained in the Standard Model. Precision measurements of quantities that are robustly predicted within the Standard Model are an important class of such searches. An example is a measurement of the proton's weak charge. The weak charge is the strength of the proton's vector coupling to the weak neutral current, and its value is a firm prediction of the Standard Model. Thus an experimental test of the prediction is well motivated as a search for new physics. A recently completed experiment at Jefferson Lab, Qweak, has the goal of making the first precision measurement of the weak charge, using parity-violating electron scattering from hydrogen at very low momentum transfer. The result from the first subset of data will be presented, as well as an overview of the data analysis for the full data set and prospects for the final result, which will provide a sensitivity to new physics at the multi-TeV scale.