Relativistic and Nuclear Structure Effects in Parity-Violating Quasielastic Electron Scattering

The parity violating longitudinal asymmetry ${\cal A}$ is calculated for quasielastic electron scattering. We use a variety of relativistic mean field models for the response of nuclear matter and $^{12}$C at a momentum transfer of q=550 MeV/c. Relativistic effects from a reduced nucleon mass, RPA correlations and vacuum polarization can all change ${\cal A}$ by a relatively large amount. These large nuclear structure corrections could make it impossible to extract strange quark matrix elements or radiative corrections to weak axial currents.