Dispersion corrections to parity violating electron scattering

TL;DR

This paper analyzes the dispersion correction to parity violating electron-proton scattering, confirming a 6% correction for the QWEAK experiment and identifying key parameters needed to reduce theoretical uncertainties.

Contribution

It provides a detailed study of the dispersion correction, confirming its size and outlining parameters crucial for minimizing theoretical uncertainties in weak charge measurements.

Findings

Dispersion correction is approximately 6% for QWEAK.

Parameters must be constrained within 30% to control uncertainties.

Detailed analysis supports previous larger estimates of the correction.

Abstract

We consider the dispersion correction to elastic parity violating electron-proton scattering due to \gammaZ exchange. In a recent publication, this correction was reported to be substantially larger than the previous estimates. In this paper, we study the dispersion correction in greater detail. We confirm the size of the disperion correction to be 6% for the QWEAK experiment designed to measure the proton weak charge. We enumerate parameters that have to be constrained to better than relative 30% in order to keep the theoretical uncertainty for QWEAK under control.