Transverse momentum dependent gluon distributions at the LHC

TL;DR

This paper discusses how linearly polarized gluons inside unpolarized protons influence transverse momentum distributions and azimuthal asymmetries in various particle production processes at the LHC, enabling potential extraction of gluon distributions.

Contribution

It introduces the study of linearly polarized gluon distributions at the LHC and their impact on measurable observables in hadronic collisions.

Findings

Potential to extract polarized and unpolarized gluon distributions from LHC data.

Identification of azimuthal asymmetries in photon and quarkonium production.

Insights into the process and energy scale dependence of gluon distributions.

Abstract

Linearly polarized gluons inside an unpolarized proton contribute to the transverse momentum distributions of (pseudo)scalar particles produced in hadronic collisions, such as Higgs bosons and quarkonia with even charge conjugation ($\eta_c$, $\eta_b$, $\chi_{c0}$, $\chi_{b0}$). Moreover, they can produce azimuthal asymmetries in the associated production of a photon and a $J/\psi$ or a $\Upsilon$ particle, in a kinematic configuration in which they are almost back to back. These observables, which can be measured in the running experiments at the LHC, could lead to a first extraction of both the polarized and the unpolarized gluon distributions and allow for a study of their process and energy scale dependences.