Gluon gravitational form factors of protons from charmonium photoproduction

TL;DR

This paper analyzes gluon gravitational form factors of protons using charmonium photoproduction data, providing insights into the proton's internal structure and mechanical properties through a global fit of experimental results.

Contribution

It introduces a comprehensive analysis connecting gluon GFFs with experimental photoproduction data and combines this with quark contributions to explore the proton's mechanical characteristics.

Findings

Determined gluon GFFs as functions of momentum transfer $t$

Extracted the total $D$-term from combined data

Provided new constraints on gluon contributions to proton structure

Abstract

Inspired by the recent near-threshold $J/\psi$ photoproduction measurements, we discuss gluon gravitational form factors (GFFs) and internal properties of the proton. This work presents a complete analysis of the proton gluon GFFs connecting the gluon part of the energy-momentum tensor and the heavy quarkonium photoproduction. In particular, a global fitting of the $J/\psi$ differential and total cross section experimental data is used to determine the gluon GFFs as functions of the squared momentum transfer $t$. Combined with the quark contributions to the $D$-term form factor extracted from the deeply virtual Compton scattering experiment, the total $D$-term is obtained to investigate their applications in describing the proton mechanical properties. These studies provide a unique perspective on investigating the proton gluon GFFs and important information for enhancing QCD constraints on the gluon GFFs.