High-accuracy calculation of 6s → 7s parity-nonconserving amplitude in Cs

We calculated the parity-nonconserving (PNC) 6s --> 7s amplitude in Cs. In the Dirac-Coulomb approximation our result is in good agreement with other calculations. Breit corrections to the PNC amplitude and to the Stark-induced amplitude P are found to he -0.4% and -1%. respectively. The weak charge of Cs-133 is Q(w) = -72.5 +/- 0.7 in agreement with the standard model.