# Twist-3 fragmentation contribution to polarized hyperon production in unpolarized hadronic collisions

## TL;DR

This paper calculates the contribution of twist-3 fragmentation functions to the polarization of hyperons produced in unpolarized proton-proton collisions, addressing a long-standing challenge in describing hyperon polarization.

## Contribution

It provides the first leading-order calculation of twist-3 fragmentation effects on hyperon polarization within collinear factorization, incorporating QCD relations among functions.

## Key findings

- Derived the leading-order cross section for twist-3 fragmentation contributions.
- Clarified the role of twist-3 functions in hyperon polarization.
- Enhanced understanding of polarization mechanisms in hadronic collisions.

## Abstract

It has been known for a long time that hyperons produced in hadronic collisions are polarized perpendicular to the production plane of the reaction. This effect cannot be described by using twist-2 collinear parton correlators only. Here we compute the contribution of twist-3 fragmentation functions to the production of transversely polarized hyperons in unpolarized proton-proton collisions in the framework of collinear factorization. By taking into account the relations among the relevant twist-3 fragmentation functions which follow from the QCD equation of motion and the Lorentz invariance property of the correlators, we present the leading-order cross section for this term.