Probing gluon GTMDs through exclusive coherent diffractive processes

TL;DR

This paper extends a gluon GTMD model to better describe diffractive processes at HERA and discusses the challenges in unifying data for different diffractive processes, providing predictions for future experiments.

Contribution

It introduces an improved gluon GTMD model and analyzes its tension with experimental data, highlighting the need for further measurements to unify the description.

Findings

Significant tension between diffractive dijet and J/ψ production data regarding t-dependence.

Predictions for upcoming EIC, UPC, LHC, and RHIC experiments to test the model.

Discussion on how GTMDs go beyond GPDs in describing diffractive processes.

Abstract

We extend a previous GTMD model to improve the description of the HERA data on diffractive dijet production, and include exclusive coherent diffractive $J/\psi$ production data. We find that within our gluon GTMD model context and assumptions, there is considerable tension between the data for these two types of processes concerning the $t$ dependence. Photo- and electroproduction data for protons and nuclei from EIC and UPC data from LHC and RHIC can help to establish whether a common GTMD description is possible, as one would expect, and to facilitate studies of such data we provide predictions for the various experiments. We point out explicitly in which sense this goes beyond the description in terms of GPDs.