Gamma-Z box contributions to parity violating elastic e-p scattering

TL;DR

This paper analyzes the gamma-Z box contributions to parity-violating elastic electron-proton scattering, providing an analytic calculation and numerical evaluation that supports a debated factor and aligns with experimental uncertainty requirements.

Contribution

It offers an analytic expression for a gamma-Z box integral and supports a specific choice of a debated factor, improving the understanding of radiative corrections in PV e-p scattering.

Findings

Numerical gamma-Z box evaluation agrees with previous results within errors.

The analysis supports a specific debated factor in the gamma-Z contribution.

The results are within current experimental uncertainty bounds.

Abstract

Parity-violating (PV) elastic electron-proton scattering measures Q-weak for the proton, $Q_W^p$. To extract $Q_W^p$ from data, all radiative corrections must be well-known. Recently, disagreement on the gamma-Z box contribution to $Q_W^p$ has prompted the need for further analysis of this term. Here, we support one choice of a debated factor, go beyond the previously assumed equality of electromagnetic and gamma-Z structure functions, and find an analytic result for one of the gamma-Z box integrals. Our numerical evaluation of the gamma-Z box is in agreement within errors with previous reports, albeit somewhat larger in central value, and is within the uncertainty requirements of current experiments.