Testing the process dependence of the Sivers function via hadron distributions inside a jet

TL;DR

This paper investigates the process dependence of the Sivers function by analyzing azimuthal distributions of pions inside jets and single jet asymmetries in polarized proton collisions, aiming to test its universality.

Contribution

It introduces a method to isolate the Sivers contribution in jet-related observables and compares predictions with and without color gauge factors to test process dependence.

Findings

Predictions with and without gauge factors are similar in size but opposite in sign.

Both processes can effectively discriminate between different theoretical approaches.

Results provide a pathway to test the universality of the Sivers function.

Abstract

We study the process dependence of the Sivers function by considering the impact of color-gauge invariant initial and final state interactions on transverse spin asymmetries in proton-proton reactions within the framework of the transverse momentum dependent (TMD), generalized parton model. To this aim, we consider the azimuthal distribution of leading pions inside a fragmenting jet as well as single inclusive jet asymmetry in polarized proton proton collisions. In contrast to single inclusive pion production, in both cases we can isolate the Sivers contribution and thereby study its process dependence. The predictions for the Sivers asymmetry obtained with and without inclusion of color gauge factors are comparable in size but with opposite signs. We conclude that both processes represent unique opportunities to discriminate among the two approaches and test the universality properties of the Sivers function in hadronic reactions.