QED corrections to the parity-nonconserving 6s-7s amplitude in $^{133}$Cs

Abstract

The complete gauge-invariant set of the one-loop QED corrections to the parity-nonconserving 6s-7s amplitude in $^{133}$Cs is evaluated to all orders in $αZ$ using a local version of the Dirac-Hartree-Fock potential. The calculations are peformed in both length and velocity gauges for the absorbed photon. The total binding QED correction is found to be -0.27(3)%, which differs from previous evaluations of this effect. The weak charge of $^{133}$Cs, derived using two most accurate values of the vector transition polarizability $β$, is $Q_W=-72.57(46)$ for $β= 26.957(51) a_{\rm B}^3$ and $Q_W=-73.09(54)$ for $β= 27.15(11)a_{\rm B}^3 $. The first value deviates by $1.1σ$ from the prediction of the Standard Model, while the second one is in perfect agreement with it.