Studying Two-Photon Exchange in Deep Inelastic Scattering with the HERA Data

TL;DR

This paper investigates the impact of two-photon exchange effects on deep inelastic scattering measurements using HERA and SLAC data, aiming to clarify their role in proton structure function analysis.

Contribution

It provides the first constraints on higher-order QED effects, specifically TPE, in inclusive DIS cross sections using existing experimental data.

Findings

No significant deviation from unity in the  and  DIS cross section ratios.

Constraints placed on the magnitude of TPE contributions in DIS.

Implications for the interpretation of proton structure functions.

Abstract

Two-photon exchange (TPE) is one of the leading explanations for discrepancies in measurements of the proton electromagnetic form factors. It has been proposed that TPE could impact not only elastic scattering, but also the cross sections for both inclusive deep inelastic scattering (DIS) and semi-inclusive DIS, thereby affecting the interpretation of DIS structure functions in terms of parton distributions. It is expected that higher-order QED effects such as TPE should manifest as a deviation from unity in the ratio of \epp and \emp DIS cross sections. We use the existing inclusive $e^{\pm}p$ DIS data from HERA and SLAC to constrain higher-order QED effects on inclusive DIS.