Sivers and Collins Effects: from SIDIS to Proton-Proton Inclusive Pion Production

TL;DR

This paper investigates whether Sivers, Collins, and transversity functions derived from SIDIS and e+e- data can explain large SSAs in proton-proton pion production within the TMD factorization framework, considering limited x-range coverage.

Contribution

It analyzes the universality of Sivers functions and their role in explaining SSAs in proton-proton collisions, accounting for different large-x behaviors.

Findings

No clear evidence of universality breaking for Sivers functions.

Sivers and transversity functions can partially explain SSAs within experimental constraints.

Different large-x behaviors of Sivers functions are considered due to limited SIDIS data.

Abstract

We consider the Sivers, Collins and transversity functions as extracted from SIDIS and e+e- experimental data and investigate to what extent they might explain the large Single Spin Asymmetries (SSA) observed in proton-proton inclusive processes. This phenomenological study is performed within the TMD factorization scheme. As the SIDIS data cover only a limited range of x values (x < 0.3), we allow for different large $x$ behaviours of the SIDIS Sivers functions and transversity distributions. We conclude that, within the available experimental constraints, one cannot observe any clear universality breaking effect for the Sivers functions.