A novel method of formulating the twist-3 gluon fragmentation function contribution to hyperon polarization in the proton-proton collision is presented. The method employs a covariant gauge and takes full advantage of the Ward-Takahashi identities before performing the collinear expansion. It provides a robust way of constructing the general cross section formula, and also a clear understanding for the absence of the ghost-like terms in the twist-3 cross section in the leading order with respect to the QCD coupling constant.
@article{arxiv.2206.14965,
title = {A New Derivation of the Twist-3 Gluon Fragmentation Contribution to Polarized Hyperon Production},
author = {Riku Ikarashi and Yuji Koike and Kenta Yabe and Shinsuke Yoshida},
journal= {arXiv preprint arXiv:2206.14965},
year = {2022}
}