Back-to-back isolated photon-quarkonium production at the LHC and the transverse-momentum-dependent distributions of the gluons in the proton

TL;DR

This paper proposes using back-to-back isolated photon-quarkonium production at the LHC to experimentally determine gluon transverse-momentum-dependent distributions in the proton, providing a new way to probe gluon polarization and momentum.

Contribution

It introduces a novel method to measure gluon TMDs through specific photon-quarkonium production processes at the LHC.

Findings

Calculated transverse-momentum-dependent effects for the process.

Discussed the feasibility of measuring gluon TMDs.

Highlighted the potential to determine gluon polarization distributions.

Abstract

The study of a quasi back-to-back isolated pair made of a heavy quarkonium, such as a J/psi or a Upsilon, and a photon produced in proton-proton collisions at the LHC, is probably the optimal way to get right away a first experimental determination of two gluon transverse-momentum-dependent distributions (TMDs) in an unpolarized proton, f1^g and h1^perp,g the latter giving the distribution of linearly polarized gluons. To substantiate this, we calculate the transverse-momentum-dependent effects that arise in the process under study and discuss the feasibility of their measurements.