Gluon TMDs in quarkonium production

TL;DR

This paper investigates gluon transverse momentum dependent parton distribution functions (TMD PDFs) in quarkonium production at hadron colliders, focusing on low-mass states like eta_b to explore nonperturbative gluon structure.

Contribution

It develops a factorization framework for the eta_b transverse momentum spectrum using effective field theory, enabling precise phenomenological predictions at NNLL and NLO accuracy.

Findings

Predictions for unpolarized cross sections at low transverse momentum

Framework for extracting nonperturbative gluon information

Potential to inform gluon content in proton from future data

Abstract

I report on our investigations into the impact of (un)polarized transverse momentum dependent parton distribution functions (TMD PDFs or TMDs) for gluons at hadron colliders, especially at A Fixed Target Experiment at the LHC (AFTER@LHC). In the context of high energy proton-proton collisions, we look at final states with low mass (e.g. $\eta_b$) in order to investigate the nonperturbative part of TMD PDFs. We study the factorization theorem for the $q_T$ spectrum of $\eta_b$ produced in proton-proton collisions relying on the effective field theory approach, defining the tools to perform phenomenological investigations at next-to-next-to-leading log (NNLL) and next-to-leading order (NLO) accuracy in the perturbation theory. We provide predictions for the unpolarized cross section and comment on the possibility of extracting nonperturbative information about the gluon content of the proton once data at low transverse momentum are available.