PRECISION MEASUREMENTS OF PARITY VIOLATION AND THE WEAK MIXING ANGLE IN MØLLER SCATTERING

Abstract

We report an observation of a parity-violating asymmetry in fixed target electron-electron (Møller) scattering at a four-momentum transfer Q2 = 0.03 ( GeV/c )2. This is a most precise measurement of parity nonconservation to date, and leads to a determination of the electron's weak charge and of the value of the effective weak mixing angle [Formula: see text], which is consistent with the Standard Model expectation at the current level of precision. The comparison between the measurements of the weak mixing angle at Q2 = 0.03 ( GeV/c )2 and at the Z0 pole establishes the running of sin 2θW with 6.5σ significance.