Comprehensive description of $J/\psi$ production in proton-proton collisions at collider energies

TL;DR

This paper combines CGC and NRQCD formalisms to accurately describe $J/$ production in proton-proton collisions at low transverse momentum, matching experimental data and bridging to NLO collinear approaches.

Contribution

It introduces a combined CGC+NRQCD approach to compute $J/$ production, providing detailed insights into color singlet and octet contributions and matching NLO results.

Findings

Excellent agreement with experimental cross-sections and distributions.

Quantification of color singlet contribution (~10%).

Smooth transition to NLO collinear NRQCD results.

Abstract

We employ a small $x$ Color Glass Condensate (CGC)+ Non-Relativistic QCD (NRQCD) formalism to compute $J/\psi$ production at low $p_\perp$ in proton-proton collisions at collider energies. Very good agreement is obtained for total cross-sections, rapidity distributions and low momentum $p_\perp$ distributions. Similar agreement is obtained for $\psi^\prime$ production. We observe an overlap region in $p_\perp$ where our results match smoothly to those obtained in a next-to-leading order (NLO) collinearly factorized NRQCD formalism. The relative contribution of color singlet and color octet contributions can be quantified in the CGC+NRQCD framework, with the former contributing approximately $10\%$ of the total cross-section.