Low-Energy Measurements of the Weak Mixing Angle

We review the status of precision measurements of weak neutral-current interactions, mediated by the Z 0 boson, at Q 2 ≪M 2 Z . They can be used to extract values for the weak mixing angle Formula: see text, a fundamental parameter of the Formula: see text electroweak sector of the Standard Model. Apart from providing a comprehensive test of the electroweak theory at the quantum-loop level, such measurements allow indirect access to New Physics effects at and beyond the TeV scale. After providing a theoretical introduction and a brief overview of the three most precise low-Q 2 weak mixing angle determinations, we describe the ongoing experimental program and prospects for future, more sensitive studies. We also compare the sensitivities of planned and proposed measurements with physics beyond the Standard Model.