Heavy quark pair production in high energy pA collisions: Quarkonium

TL;DR

This paper investigates quarkonium production in high-energy pA collisions using the color glass condensate framework, focusing on the transverse momentum spectrum and nuclear modification factors at RHIC and LHC energies.

Contribution

It introduces a model combining the color evaporation approach with small-x gluon distributions from the BK equation, analyzing different gluon distribution descriptions for quarkonium production.

Findings

Transverse momentum spectra for J/psi and Upsilon(1S) are computed.

Nuclear modification factors show suppression patterns at different energies.

Momentum broadening effects are analyzed across rapidities and saturation scales.

Abstract

Quarkonium production in high-energy proton (deuteron)-nucleus collisions is investigated in the color glass condensate framework. We employ the color evaporation model assuming that the quark pair produced from dense small-x gluons in the nuclear target bounds into a quarkonium outside the target. The unintegrated gluon distribution at small Bjorken x in the nuclear target is treated with the Balitsky-Kovchegov equation with running coupling corrections. For the gluons in the proton, we examine two possible descriptions, unintegrated gluon distribution and ordinary collinear gluon distribution. We present the transverse momentum spectrum and nuclear modification factor for J/psi production at RHIC and LHC energies, and those for Upsilon(1S) at LHC energy, and discuss the nuclear modification factor and the momentum broadening by changing the rapidity and the initial saturation scale.