Probing Gluon TMDs at a Future EIC

TL;DR

This paper explores how gluon transverse momentum dependent distributions (TMDs) can be measured at a future Electron-Ion Collider by analyzing azimuthal asymmetries in heavy quark and dijet production, and investigates their behavior at small x using a theoretical model.

Contribution

It provides theoretical predictions for measurable gluon TMD observables at a future EIC and examines their small-x behavior using the McLerran-Venugopalan model, including process dependence and sign change predictions.

Findings

Identifies kinematic regions where gluon TMD asymmetries are measurable.

Predicts the sign change of the gluon Sivers function and other T-odd distributions.

Provides bounds for azimuthal asymmetries in future EIC experiments.

Abstract

Gluon TMDs can be accessed through the analysis of azimuthal asymmetries for heavy quark pair and dijet production in electron-proton collisions, similarly to the way quark TMDs are commonly extracted from semi-inclusive deep-inelastic scattering data. We calculate the upper bounds for these observables, showing in which kinematic regions they are large enough to be measured in future experiments at an Electron-Ion Collider. Moreover, we study their behavior in the small-$x$ region, adopting a McLerran-Venugopalan model for unpolarized and linearly polarized gluon distributions. By comparison with related observables at RHIC and LHC, we expect to gather information on the process dependence of the gluon TMDs and to test our prediction of a sign change of the gluon Sivers function and two other $T$-odd gluon distributions.