Exclusive $J/\psi$ process tamed to probe the low $x$ gluon

TL;DR

This paper investigates whether exclusive J/ meson production at the LHC can be used to constrain the low x gluon parton distribution function, addressing theoretical challenges and exploring alternative approaches.

Contribution

It demonstrates the potential to use exclusive J/ data in global gluon PDF analyses despite theoretical complexities and discusses the application of k_T factorization.

Findings

Potential to constrain low x gluon PDF using exclusive J/ data

Identification of challenges in collinear factorization approach

Discussion of k_T factorization as an alternative method

Abstract

We address the question as to whether data for J/\psi mesons produced exclusively in the forward direction at the LHC can be used in global parton analyses (based on collinear factorization) to pin down the low x gluon PDF. We show that it may be possible to overcome the problems that (i) the process is described by a skewed or Generalized Parton Distribution (GPD), (ii) it is very sensitive to the choice of factorization scale and (iii) there is bad LO, NLO,... perturbative stability to the predictions. However, we start by briefly explaining how the alternative k_T factorization approach has been used to describe the process.