Updated analysis of near-threshold heavy quarkonium production for probe of proton's gluonic gravitational form factors

TL;DR

This paper revises previous analyses of near-threshold heavy quarkonium production, incorporating new experimental and lattice data to better probe the gluonic gravitational form factors of the proton, especially at large momentum transfer.

Contribution

It provides an updated analysis of heavy quarkonium production near threshold, emphasizing the role of recent experimental and lattice results in extracting gluonic GFFs.

Findings

Revised the previous theoretical results with new data.

Highlighted the significance of large momentum transfer in the analysis.

Confirmed the dominance of gluonic gravitational form factors in the process.

Abstract

There has been growing interest in the near-threshold production of heavy quarkonium which can access the gluonic structure in the nucleon. Previously we studied this process with quantum chromodynamics (QCD) and showed that it can be factorized with the gluon generalized parton distributions (GPDs) in the heavy quark limit. We further argued that the hadronic matrix element is dominated by its leading moments corresponding to the gluonic gravitational form factors (GFFs) in this limit. Since then, there have been many new developments on this subject. More experimental measurements have been made and published, and the lattice simulation of gluonic GFFs has been improved as well. In this work, we make an important revision to a previous result and perform an updated analysis with the new inputs. We also study the importance of the large momentum transfer to extract these gluonic structures reliably in this framework.