Calculation of parity non-conservation in Cesium and possible deviation from the Standard Model

Full text: There is an ongoing discussion on whether measurements of parity non-conservation (PNC) in atoms can be used to study new physics beyond the standard model. There were even indications that the PNC measurements in Cs disagree with the standard model. However, the interpretation of such measurements is limited by the accuracy of atomic calculations. We have made considerable efforts to overcome this limitation by further analysis of the correlation, Breit, and radiative corrections to PNC in Cs. Our new result for the 6s-7s PNC E1 transition amplitude in caesium is EPNC = 0.902 (1 ± 0.7%ieaB(QW/N). This represents an improvement in the accuracy of the calculation from the 1% error claimed in 1989. This result corresponds to a nuclear weak charge for Cs, QW = -72.39 (1 ± 0.4%(exp) ± 0.7% (theory)). We conclude that there is no significant deviation from the Standard Model value -73.09(3)