We study the production of polarized Λ-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 Λ-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.
@article{arxiv.1810.08645,
title = {Polarized hyperon production in single-inclusive electron-positron annihilation at next-to-leading order},
author = {Leonard Gamberg and Zhong-Bo Kang and Daniel Pitonyak and Marc Schlegel and Shinsuke Yoshida},
journal= {arXiv preprint arXiv:1810.08645},
year = {2019}
}