Implications of exclusive $J/\psi$ photoproduction in a tamed collinear factorisation approach to NLO

TL;DR

This paper compares conventional and refined collinear factorisation approaches at NLO for exclusive $J/psi$ photoproduction, highlighting the potential to better constrain low $x$ gluon PDFs crucial for future global analyses.

Contribution

It introduces a refined approach with low $x$ resummation and low $Q_0$ subtraction, enhancing the understanding of gluon PDFs in exclusive $J/psi$ photoproduction.

Findings

Refined approach with low $x$ resummation improves predictions.

Comparison shows potential to constrain low $x$ gluon PDFs.

Highlights importance for future global PDF fits.

Abstract

We discuss exclusive $J/\psi$ photoproduction, initially in conventional collinear factorisation at NLO and then subsequently in a refined approach with a programme of low $x$ resummation and implementation of a crucial low $Q_0$ subtraction included. We compare and contrast predictions in both frameworks and remark about the possibility to constrain and ultimately determine the low $x$ and low scale gluon PDF, emphasising the significance of this for future global PDF analyses.