Partonic calculation of $\gamma Z$ Exchange Corrections to Parity-Violating Elastic Electron-Proton Scattering

TL;DR

This paper calculates $ ext{γ}Z$ exchange corrections to parity-violating electron-proton scattering using a parton model with GPDs, revealing that common zero-momentum-transfer approximations overestimate effects at forward angles.

Contribution

It introduces a parton model calculation of $ ext{γ}Z$ corrections with GPDs and critically assesses the zero-momentum-transfer approximation's validity.

Findings

Zero-momentum-transfer approximation overestimates effects at forward angles.

Parton model with GPDs provides a more accurate correction calculation.

Significant deviation from previous approximations at small scattering angles.

Abstract

We calculate $\gamma Z$ exchange corrections to the parity-violating asymmetry of the elastic electron-proton scattering in a parton model using the formalism of generalized parton distributions(GPDs). We also examine the validity of the zero-momentum-transfer approximation adopted in the literatures and find that it overestimates the $\gamma Z$ exchange effect significantly at the forward scattering angles.