On effects of multiple gluons in $J/\psi$ hadroproduction

TL;DR

This paper calculates the impact of three-gluon mechanisms on $J/$ production in high-energy hadron collisions, revealing significant corrections at collider energies and discussing implications for nuclear effects.

Contribution

It introduces a perturbative QCD calculation of three-gluon contributions to $J/$ production within the $k_T$ factorization framework, highlighting their importance at high energies.

Findings

Rescattering significantly corrects the standard cross-section at Tevatron and LHC energies.

Double gluon density enhances the three-gluon contribution at small $x$.

Possible role in anti-shadowing effects in proton-nucleus collisions.

Abstract

The three-gluon contribution to $J/\psi$ hadroproduction is calculated within perturbative QCD in the $k_T$ factorization framework. This mechanism involves double gluon density and enters at a non-leading twist, but it is enhanced at large energies due to large double gluon density at small $x$. We obtain results for differential $p_T$-dependent cross-sections for all $J/\psi$ polarisations. The rescattering contribution is found to provide a significant correction to the standard leading twist cross-section at the energies of the Tevatron or the LHC at moderate $p_T$. We also discuss a possible contribution of the rescattering correction to the anti-shadowing effect for $J/\psi$ production in proton - nucleus collisions.