Parity nonconservation in thallium

Abstract

We report a calculation of the parity nonconserving (PNC) $E1$ amplitude for the ${6p}_{1/2}\ensuremath{\rightarrow}{6p}_{3/2}$ transition in ${}^{205}\mathrm{Tl}.$ Our result for the reduced matrix element is ${(E1)}_{\mathrm{PNC}}=\ensuremath{-}(66.7\ifmmode\pm\else\textpm\fi{}1.7)\ifmmode\times\else\texttimes\fi{}\mathrm{i}{10}^{\ensuremath{-}11}(\ensuremath{-}{Q}_{W}/N) \mathrm{a}.\mathrm{u}.$ Comparison with the experiment of Vetter et al. [Phys. Rev. Lett. 74, 2658 (1995)] gives the following result for the weak charge of ${}^{205}\mathrm{Tl}: {Q}_{W}{/Q}_{W}^{\mathrm{SM}}=0.97(\ifmmode\pm\else\textpm\fi{}{0.01)}_{\mathrm{expt}}(\ifmmode\pm\else\textpm\fi{}{0.03)}_{\mathrm{theor}},$ where ${Q}_{W}^{\mathrm{SM}}=\ensuremath{-}116.7\ifmmode\pm\else\textpm\fi{}0.1$ 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.