Two-Photon Exchange in Electron-Proton Elastic Scattering: Theory Update

TL;DR

This paper reviews recent theoretical advances in understanding two-photon exchange effects in elastic electron-proton scattering, which may explain discrepancies in proton form factor measurements at high momentum transfers.

Contribution

It provides an updated theoretical framework for two-photon exchange effects and discusses their potential impact on experimental results.

Findings

Two-photon exchange effects can account for measurement discrepancies.

Measurable effects predicted and currently under experimental investigation.

Updated theory aligns with recent experimental data.

Abstract

Recent theoretical developments in the studies of two-photon exchange effects in elastic electron-proton scattering are reviewed. Two-photon exchange mechanism is considered a likely source of discrepancy between polarized and unpolarized experimental measurements of the proton electric form factor at momentum transfers of several GeV$^2$. This mechanism predicts measurable effects that are currently studied experimentally.