Production of $J/\psi$ quarkonia in color evaporation model based on $k_{T}$-factorization

TL;DR

This paper investigates $J/$ production using a modified color evaporation model within the $k_T$-factorization framework, exploring different gluon distributions and process contributions to improve agreement with experimental data.

Contribution

It introduces a new approach to the color evaporation model incorporating $k_T$-factorization and assesses the impact of various unintegrated gluon distributions and higher-order processes.

Findings

Poor description of large transverse momentum $J/$ with JH-2013 UGDF

Including $2 o 3$ processes improves the model's accuracy

Explicit treatment of higher-order processes enhances $J/$ production predictions

Abstract

We use a new approach to color evaporation model (CEM) for quarkonium production. The production of $c\bar c$ pairs is performed within $k_T$-factorization approach using different unintegrated gluon distribution functions (UGDF) from the literature. We include all recent improvements to color evaporation model. We get poor description of the large transverse momentum distributions of $J/\psi$ with the JH-2013 CCFM-based UGDF. Here explicit inclusion of $2 \to 3$ processes considerably improves the situation. Similar effects are discussed in the context of the KMR UGDF.