Transverse Lambda polarization at high energy colliders

TL;DR

This paper presents new theoretical predictions for transverse Lambda hyperon polarization in high-energy proton-proton collisions, aiming to clarify production mechanisms and polarization origins using a factorized approach.

Contribution

It introduces novel expressions and predictions for Lambda polarization in pp collisions, accounting for uncertainties in fragmentation functions and SU(3) symmetry breaking.

Findings

Predictions highlight the role of gluons and sea quarks in polarization.

Uncertainties due to fragmentation functions are quantitatively analyzed.

The approach provides a framework for future experimental tests.

Abstract

Measurements of transverse polarization of Lambda hyperons produced in high energy pp collisions may help to address several open issues about Lambda production and polarization mechanisms, such as the amount of SU(3) breaking, the importance of gluons and sea quarks, and the origin of spontaneous Lambda polarization. The process p + p -> Lambda^\uparrow + jet + X at midrapidity is ideally suited for this purpose, for instance at LHC's ALICE experiment. New expressions and predictions are presented for the transverse Lambda polarization in this process, within a factorized description which involves transverse momentum and spin dependence in the fragmentation process. Uncertainties from the unpolarized Lambda fragmentation functions, due to the unknown magnitude of SU(3) breaking and the apparent inconsistency between pp and e^+ e^- data, are investigated.