High-precision measurements of atomic parity-nonconserving transitions in cesium when coupled with calculations of similar accuracy allow for a precise determination of $Q_W$, the weak nuclear charge. When expressed in terms of the $Z$ mass, radiative corrections to $Q_W$ are insensitive to the top-quark mass, so such a determination of $Q_W$ allows a particularly sensitive probe of radiative corrections depending on new physics. While the wave function of cesium, the atom in which the most accurate measurements have been made, is extremely complex, atomic theory has advanced to a point where predictions accurate to 1% can be made. This paper describes such a calculation with particular emphasis on the question of the reliability of the atomic theory. Particle-physics implications following from the present state of theory and experiment are discussed, and prospects for more accurate work described.

• Received 28 October 1991

DOI:https://doi.org/10.1103/PhysRevD.45.1602