Compilation and analysis of charge asymmetry measurements from electron and positron scattering on nucleon and nuclei

TL;DR

This paper compiles and analyzes charge asymmetry data from electron and positron scattering on nucleons and nuclei, comparing it to models and examining the two-photon exchange mechanism's role.

Contribution

It provides a comprehensive review of existing data and tests the two-photon exchange hypothesis against experimental results, finding no evidence for its significant contribution.

Findings

Existing data do not support two-photon exchange as explanation for form factor discrepancies.

The compiled data exclude two-photon exchange effects at 0.05 significance level.

No observable charge asymmetry evidence from current measurements.

Abstract

World data on the lepton-charge asymmetry in the elastic and inelastic lepton scattering off the proton and nuclei are compiled and discussed. After reviewing the published results, we compare the elastic data to a model calculation of the two-photon exchange mechanism. We show that the existing data do not provide any evidence for the two-photon contribution. At significance level 0.05 the data allow to exclude the two-photon exchange as an explanation for the difference between Rosenbluth and polarization measurements of proton electromagnetic form factors.