Parity non-conservation in thallium

Abstract

We report a new calculation of the parity non-conserving E1 amplitude for the 6p_{1/2} -> 6p_{3/2} transition in Tl. Our result for the reduced matrix element is $E1_{PNC}=-(66.7 \pm 1.7) i 10^{-11} (-Q_W/N)$ a.u. Comparison with the experiment of Vetter et al [PRL,{\bf 74},2658 (1995)] gives the following result for the weak charge of $^{205}$Tl: $Q_W/Q_W^{SM} = 0.97 (\pm 0.01)_{expt} (\pm 0.03)_{theor}$, where $Q_W^{SM}=-116.7$ is the standard model prediction. This result confirms an earlier conclusion based on the analysis of a Cs experiment that atomic PNC experiments are in agreement with the standard model.