Investigating the transverse momentum dependent gluon Sivers function in quarkonium production at $pp$ colliders

TL;DR

This paper reviews the use of the TMD approach to study the gluon Sivers function via quarkonium production in polarized proton collisions, highlighting current efforts and future prospects at RHIC, LHC, and NICA.

Contribution

It summarizes ongoing research constraining the gluon Sivers function through single spin asymmetries in quarkonium and other hadron productions in polarized proton collisions.

Findings

Progress in constraining the gluon Sivers function at RHIC.

Potential for future measurements at LHC and NICA.

Enhanced understanding of hadron structure in high-energy collisions.

Abstract

In this contribution, we will present a short overview of the transverse momentum dependent (TMD) approach as a tool for studying the 3-dimensional structure of hadrons in high-energy (un)polarized hadron collisions. We will then summarize the present status of a running research programme that aims at constraining the poorly known transverse momentum dependent gluon Sivers function, through the study of single spin asymmetries in quarkonium (mainly $J/\psi$), pion, and $D$-meson production in polarized proton-proton collisions at RHIC. Finally, we will shortly discuss perspectives for this field of research, emphasizing in particular its role in the physics programme of LHC in the fixed-target setup and NICA.