Exclusive production of heavy quarkonia as a probe of the low x and low scale gluon PDF

TL;DR

This paper investigates how exclusive $J/$ photoproduction at LHCb can be used to constrain the gluon parton distribution function at low $x$ and low $Q$, improving theoretical predictions through resummation and power corrections.

Contribution

It introduces a method to refine gluon PDF predictions at low $x$ and $Q$ by resumming small-$x$ logarithms and applying power corrections, based on recent LHCb data.

Findings

Enhanced theoretical predictions for $J/\psi$ photoproduction.

Constraints on the gluon PDF at low $x$ and $Q$.

Improved understanding of gluon behavior in the low-$x$, low-$Q$ regime.

Abstract

We discuss the exclusive $J/\psi$ photoproduction process, as measured recently at LHCb, as a means of constraining and ultimately determining the low $x$ and low $Q$ gluon PDF. The scale dependence of the theoretical prediction for this process is shown to be systematically improved via a taming of the known $\bar{\text{MS}}$ result, this amounts to resumming logarithmically enhanced small-$x$ terms and implementing a small-$Q$ power correction. The cross section level predictions allow the behaviour of the gluon PDF in the low $(x, Q)$ domain to be determined.