# Probing Generalized Parton Distributions through the photoproduction of a $\gamma \pi$ pair

## TL;DR

This paper proposes a new method to access generalized parton distributions by studying the photoproduction of a gamma-pi pair with large invariant mass, demonstrating feasibility at JLab 12-GeV and high sensitivity to axial quark GPDs.

## Contribution

It introduces a collinear QCD factorization approach to probe GPDs via gamma-pi pair photoproduction, highlighting experimental feasibility and sensitivity.

## Key findings

- Feasibility of measuring gamma-pi photoproduction at JLab 12-GeV.
- Unpolarized cross section highly sensitive to axial quark GPDs.
- Method provides a new avenue to study GPDs in QCD.

## Abstract

We study in the framework of collinear QCD factorization the photoproduction of a $\gamma\,\pi$ pair with a large invariant mass and a small transverse momentum, as a new way to access generalized parton distributions. In the kinematics of JLab 12-GeV, we demonstrate the feasibility of this measurement and show the extreme sensitivity of the unpolarized cross section to the axial quark GPDs.