Accessing the Gluon Sivers Function at a future Electron-Ion Collider

TL;DR

This paper investigates the potential to measure the gluon Sivers function at a future Electron-Ion Collider using various processes, highlighting di-jet production as the most promising method for constraining this elusive parton distribution.

Contribution

It provides a systematic feasibility study and Monte Carlo estimates for probing the gluon Sivers function at the EIC, emphasizing the di-jet channel's effectiveness.

Findings

Di-jet production offers the best constraints on the GSF.

Future EIC data can significantly improve GSF measurements.

Single spin asymmetries in photon-gluon fusion are key to accessing the GSF.

Abstract

In this work, we present a systematic study on the feasibility of probing the largely unexplored transverse momentum dependent gluon Sivers function (GSF) in open charm production, high p$_T$ charged di-hadron and di-jet production at a future high energy, high luminosity Electron-Ion Collider (EIC). The Sivers function is a measure for the anisotropy of the parton distributions in momentum space inside a transversely polarized nucleon. It is proposed that it can be studied through single spin asymmetries in the photon-gluon fusion subprocess in electron proton collisions at the EIC. Using a well tuned Monte Carlo model for deep inelastic scattering, we estimate the possible constraints of the GSF from the future EIC data. A comparison of all the accessible measurements illustrates that the di-jet channel is the most promising way to constrain the magnitude of the GSF over a wide kinematic range.