Forward Heavy Quarkonium Productions at the LHC

TL;DR

This paper combines the Color Glass Condensate framework with Sudakov resummation to accurately describe low transverse momentum heavy quarkonium production at the LHC, aiding the study of gluon saturation.

Contribution

It introduces a consistent implementation of Sudakov resummation within the CGC formalism, improving agreement with experimental data for heavy quarkonium production.

Findings

Excellent agreement between theory and LHC data achieved.

Both small-x and Sudakov effects are crucial for accurate modeling.

Provides a foundation for future gluon saturation studies in pA collisions.

Abstract

We investigate the low transverse momentum heavy quarkonium ($J/\psi$, $\Upsilon$) productions in the forward rapidity region of $pp$ and $pA$ collisions at the LHC as an important probe to the transverse momentum tomography of the gluons in hadrons in the Color Glass Condensate (CGC) framework. By implementing the Sudakov resummation consistently in the CGC formalism, we achieve an excellent agreement between the improved CGC calculations and the LHC data. We show that both the small-$x$ and the Sudakov effects are essential for a complete description of heavy quarkonium productions in the low transverse momentum region. This provides a solid foundation to study the small-$x$ gluon saturation in a big nucleus with the future $pA$ programs at the LHC.