The gluon Sivers function and its process dependence from RHIC data

TL;DR

This paper analyzes RHIC data on single spin asymmetries in proton-proton collisions using the CGI-GPM to constrain gluon Sivers functions, highlighting the importance of initial and final state interactions.

Contribution

It provides the first constraints on gluon Sivers functions incorporating process dependence via initial and final state interactions.

Findings

Preliminary constraints on gluon Sivers functions established.

Comparison shows the importance of ISIs and FSIs in modeling asymmetries.

Results suggest process dependence significantly affects Sivers function extraction.

Abstract

We present a phenomenological analysis of available data on single spin asymmetries for pion and $D$ meson production in proton-proton collisions at RHIC within the color gauge invariant generalized parton model (CGI-GPM), which includes initial (ISIs) and final (FSIs) state interactions in a transverse momentum dependent formalism. This study allows us, for the first time, to put preliminary constraints on the two independent gluon Sivers functions entering the model. We also present a comparison with the simpler generalized parton model (without ISIs and FSIs).