Single spin asymmetries in l p --> h X processes: a test of factorization

TL;DR

This paper predicts single spin asymmetries in lepton-proton collisions using TMD factorization, proposing measurements to test the theoretical framework and improve understanding of SSAs in hadronic processes.

Contribution

It provides the first predictions for SSAs in inclusive lepton-proton processes based on TMD distributions fitted from SIDIS data, testing the universality of TMD factorization.

Findings

Predicted measurable SSAs in l p --> h X and l p --> jet + X processes.

Proposed experimental tests for TMD factorization validity.

Implications for understanding SSAs in proton-proton collisions.

Abstract

Predictions for the transverse single spin asymmetry (SSA), A_N, are given for the inclusive processes l p(transv. pol.) --> h X and l p(transv. pol.) --> jet + X, which could be measured in operating or future experiments. These estimates are based on the Sivers distributions and the Collins fragmentation functions which fit the azimuthal asymmetries measured in semi-inclusive deep inelastic scattering (SIDIS) processes (l p(transv. pol.) --> l' h X). The factorization in terms of transverse momentum dependent distribution and fragmentation functions (TMD factorization) - which supplies the theoretical framework in which SIDIS azimuthal asymmetries are analyzed - is assumed to hold also for the l p --> h X inclusive process at large P_T. A measurement of A_N would then provide a direct test of the validity of the TMD factorization in this case and would have important consequences for the study and understanding of SSAs in p p(transv. pol.) --> h X processes.