Two Photon Exchange for Exclusive Pion Electroproduction

TL;DR

This paper calculates two-photon exchange corrections to pion electroproduction cross sections, revealing significant effects at large momenta and backward angles, which are crucial for precise experimental analysis.

Contribution

It provides detailed analytic expressions for two-photon exchange corrections, including effects beyond the soft-photon approximation, for the first time in this context.

Findings

Two-photon exchange can alter cross sections by over 20% at certain kinematics.

The corrections are significant at backward angles and large momentum transfers.

Analytic formulas for radiative corrections are derived and analyzed.

Abstract

We perform detailed calculations of two-photon-exchange QED corrections to the cross section of pion electroproduction. The results are obtained with and without the soft-photon approximation; analytic expressions for the radiative corrections are derived. The relative importance of the two-photon correction is analyzed for the kinematics of several experiments at Jefferson Lab. A significant, over 20%, effect due to two-photon exchange is predicted for the backward angles of electron scattering at large transferred momenta.