Parity-Violating Electron Scattering

Measurements of parity-violating asymmetries in the scattering of longitudinally polarized electrons off unpolarized fixed targets are used to access leptonic and semi-leptonic weak neutral current amplitudes. One thrust of the current program is the measurement the elastic neutral weak amplitude at very low Q from scattering off a heavy spinless nucleus, which is sensitive to the presence of a neutron skin. A second major thrust is the neutral current elastic amplitude at very low Q off protons and electrons and in the DIS regime off deuterium, which allows precision measurements of the weak mixing angle at low energy and is thus sensitive to new physics beyond the Standard Model.