Exploring universality of transversity in proton-proton collisions

TL;DR

This paper investigates the universality of transversity in proton-proton collisions by analyzing azimuthal correlations of charged hadron pairs, comparing predictions with STAR data, and confirming transversity's role and universality in such processes.

Contribution

It provides the first test of transversity universality in proton-proton collisions using azimuthal correlation measurements and theoretical predictions based on previous extractions.

Findings

Predictions align reasonably with STAR data

Confirmed the role of transversity in proton-proton collisions

Supported the universality of transversity distribution

Abstract

We consider the azimuthal correlations of charged hadron pairs with large total transverse momentum and small relative momentum, produced in proton-proton collisions with one transversely polarized proton. One of these correlations directly probes the chiral-odd transversity parton distribution in connection with a chiral-odd interference fragmentation function. We present predictions for this observable based on previous extractions of transversity (from charged pion pair production in semi-inclusive deep-inelastic scattering) and of the interference fragmentation function (from the production of back-to-back charged pion pairs in electron-positron annihilations). All analyses are performed in the framework of collinear factorization. We compare our predictions to the recent data on proton-proton collisions released by the STAR collaboration at RHIC, and we find them reasonably compatible. This comparison confirms for the first time the predicted role of transversity in proton-proton collisions and it allows to test its universality.