Polarized hyperon production in single-inclusive electron-positron annihilation at next-to-leading order

TL;DR

This paper calculates the next-to-leading order QCD corrections to the transverse polarization of Lambda hyperons produced in electron-positron annihilation, advancing understanding of twist-3 fragmentation functions and their evolution.

Contribution

It provides the first NLO perturbative QCD calculation of twist-3 fragmentation contributions to polarized hyperon production in e+e- annihilation.

Findings

Calculated NLO hard partonic cross sections for hyperon polarization.

Derived the evolution equation for twist-3 fragmentation functions.

Highlighted the role of QCD equations of motion in the analysis.

Abstract

We study the production of polarized $\Lambda$-hyperons in electron-positron annihilation. We are particularly interested in the transverse-spin dependence of the cross section for unpolarized incident electron-positron pairs. At high energies this process may be described in the collinear twist-3 framework, where the hadronization transition of partons into a transversely polarized $\Lambda$-hyperon can be written in terms of collinear twist-3 fragmentation matrix elements. We calculate the hard partonic cross sections and interference terms in perturbative QCD to next-to-leading order accuracy. We find that the QCD equation of motion plays a crucial role in our analysis. As a byproduct, assuming the validity of QCD factorization for twist-3 observables at next-to-leading order, we derive the evolution equation for the relevant twist-3 fragmentation matrix element.