Impact of atomic parity violation measurements on precision electroweak physics

The impact of atomic parity violation experiments on the determination of the weak mixing parameter sin2θ and the Peskin-Takeuchi parameters S and T is reassessed in the light of recent electroweak measurements at CERN LEP, SLAC, and Fermilab. Since the weak charge QW provides unique information on S, its determination with a factor of 4 better accuracy than present levels can have a noticeable effect on global fits. However, the measurement of ΔQW/QW for two different isotopes provides primarily information on sin2θ. To specify this quantity to an accuracy of ±0.0004, comparable to that now provided by other electroweak experiments, one would have to determine ΔQW/QW in cesium to about 0.1% of its value, with comparable demands for other nuclei. The relative merits of absolute measurements of QW and isotope ratios for discovering effects of new gauge bosons are noted briefly. copyright 1996 The American Physical Society