Constraints on new physics from an improved calculation of parity violation in $^{133}$Cs

Abstract

We report the result of our calculation of the nuclear spin-independent parity violating electric dipole transition amplitude ($E1_{PV}$) for the $6s ~ ^2S_{1/2} - 7s ~ ^2S_{1/2}$ transition in $^{133}$Cs to an accuracy of 0.3\% using a variant of the perturbed relativistic coupled-cluster theory. In the present work, we treat the contributions of both the low-lying and high-lying excited states to the above mentioned amplitude on the same footing, thereby overcoming the limitations of previous high accuracy relativistic coupled cluster calculations. We obtain an accurate value for the vector polarizability ($\beta$) for the above transition and by combining it with the results from our present calculation of $E1_{PV}$ and the latest measurement of $Im(E1_{PV}/\beta)$, we extract the nuclear weak charge ($Q_W$); and analyze its deviation from its value in the Standard Model (SM) in order to constrain certain scenarios of new physics beyond the SM.