Gamma-Z box corrections to weak charges of heavy nuclei in atomic parity violation

TL;DR

This paper introduces a new dispersive approach to calculating gamma-Z box corrections in atomic parity violation, including a novel Pauli blocking correction, significantly refining the weak charge estimates for heavy nuclei.

Contribution

It provides the first evaluation of Pauli blocking effects in gamma-Z corrections, improving the accuracy of weak charge calculations in heavy nuclei.

Findings

Gamma-Z correction for 133-Cs is about four times larger than previous uncertainties.

Inclusion of Pauli blocking reduces the overall error in weak charge estimates.

Significant shift in gamma-Z correction impacts precision tests of the Standard Model.

Abstract

We present a new dispersive formulation of the gamma-Z box radiative corrections to weak charges of bound protons and neutrons in atomic parity violation (APV) measurements on heavy nuclei such as 133-Cs and 213-Ra. We evaluate for the first time a small but important additional correction arising from Pauli blocking of nucleons in a heavy nucleus. Overall, we find a significant shift in the gamma-Z correction to the weak charge of 133-Cs, approximately 4 times larger than the current uncertainty on the value of sin^2(theta_W), but with a reduced error compared to earlier estimates.