Atomic-beam measurement of parity nonconservation in cesium

We present a new measurement of parity nonconservation in cesium. In this experiment, a laser excited the 6S → 7S transition in an atomic beam in a region of static electric and magnetic fields. The quantity measured was the component of the transition rate arising from the interference between the parity nonconserving amplitude, 𝒞_PNC, and the Stark amplitude, βE. Our results are Im𝒞_PNC/β = − 1.65±0.13 mV/cm and C_2p= −2 ± 2, where C_2p is the proton-axial-vector–electron-vector neutral-current coupling constant. These results are in agreement with previous less precise measurements in cesium and with the predictions of the electroweak standard model. We give a detailed discussion of the experiment with particular emphasis on the treatment and elimination of systematic errors. This experimental technique will allow future measurements of significantly higher precision.