Threshold expansion of the gg(qq) -> QQ+X cross section at O(alpha_s^4)

TL;DR

This paper derives the full set of velocity-enhanced terms in the NNLO cross section for heavy-quark pair production, accounting for soft-gluon and potential-gluon effects, and proves the absence of certain soft-gluon enhancements.

Contribution

It provides the complete velocity expansion at NNLO for heavy-quark production, including soft and potential gluon effects, with a proof regarding soft-gluon coupling enhancements.

Findings

Complete velocity-enhanced terms derived at NNLO.

Soft-gluon and potential-gluon effects included.

No subleading soft-gluon enhancements to Coulomb singularity.

Abstract

We derive the complete set of velocity-enhanced terms in the expansion of the total cross section for heavy-quark pair production in hadronic collisions at next-to-next-to-leading order. Our expression takes into account the effects of soft-gluon emission as well as that of potential-gluon exchanges. We prove that there are no enhancements due to subleading soft-gluon couplings multiplying the leading Coulomb singularity.