# Charge asymmetry in elastic scattering of massive leptons on protons

## TL;DR

This paper estimates the charge asymmetry in elastic lepton-proton scattering caused by higher-order QED effects, without relying on ultrarelativistic assumptions, providing model-independent predictions relevant for experimental analysis.

## Contribution

It introduces a generalized soft-photon approximation approach that analytically calculates loop integrals with lepton mass effects, extending previous ultrarelativistic models.

## Key findings

- Provides model-independent charge asymmetry predictions
- Calculates loop integrals analytically including lepton mass
- Offers results applicable to unpolarized massive lepton scattering

## Abstract

The charge asymmetry due to higher-order QED corrections in elastic lepton-proton scattering is estimated without employing the ultrarelativistic approximation. Our calculation is performed by generalizing the soft-photon approximation approach suggested by Tsai. Corresponding loop integrals that take a form of Passarino-Veltman scalar three-point functions are calculated analytically without neglecting the mass of the lepton. Our results provide model-independent charge asymmetry predictions for scattering of unpolarized and massive leptons on proton targets. These predictions can be used in corresponding experiments to determine the contribution coming from model-dependent hard two-photon exchange processes.