On $\gamma N \to \gamma \rho N'$ at large $\gamma \rho$ invariant mass

TL;DR

This paper explores the photoproduction process involving a photon and rho meson at large invariant mass, demonstrating how it can be used to access chiral-odd and chiral-even generalized parton distributions, thus providing a new method to study transversity GPDs.

Contribution

It introduces a novel factorization approach for the process $ abla o abla$ at large invariant mass, enabling the extraction of transversity GPDs through polarization separation.

Findings

Factorization of the subprocess at dominant twist.

Access to chiral-odd GPDs via transverse rho polarization.

Potential for new insights into transversity distributions.

Abstract

Photoproduction of a pair of particles with large invariant mass is a natural extension of collinear QCD factorization theorems which have been much studied for deeply virtual Compton scattering and deeply virtual meson production. We consider the case where the wide angle Compton scattering subprocess $\gamma (q\bar q) \to \gamma \rho $ factorizes from generalized parton distribution. At dominant twist, separating the transverse (respectively longitudinal) polarization of the $\rho$ meson allows one to get access to chiral-odd (respectively chiral-even) GPDs. This opens a new way to the extraction of these elusive transversity GPDs.