Exclusive photoproduction of $\eta_{c}\gamma$ pairs with large invariant mass

TL;DR

This paper investigates the exclusive photoproduction of $\u03b3$ pairs at high invariant mass, showing it is sensitive to gluon GPDs and feasible for experimental measurement at future colliders.

Contribution

It provides the first leading-order analysis of $\u03b3$ pair production sensitivity to gluon GPDs in the collinear factorization framework.

Findings

Cross-section is sizable for experimental detection.

Process sensitive to unpolarized gluon GPD $H_g$.

Feasible at Electron-Ion Collider and LHC ultraperipheral collisions.

Abstract

In this preprint we analyzed the exclusive photoproduction of $\eta_{c}\gamma$ pairs in the collinear factorization framework and evaluated its cross-section in leading order in the strong coupling $\alpha_{s}$. We found that this process is mostly sensitive to the behavior of the unpolarized gluon GPD $H_{g}$ in the Efremov-Radyushkin-Brodsky-Lepage kinematics. We estimated numerically the cross-section and the expected counting rates in the kinematics of middle-energy photoproduction experiments which can be realized at the future Electron-Ion Collider and in the kinematics of ultraperipheral collisions at LHC. We found that the cross-section is sufficiently large for dedicated experimental study.