Two-loop QCD helicity amplitudes for $g\,g \to Z\,g$ and $g\,g \to Z\,\gamma $

TL;DR

This paper calculates two-loop helicity amplitudes for gluon fusion processes producing Z bosons with a jet or photon, providing essential ingredients for next-to-leading order corrections in particle physics predictions.

Contribution

It presents the first two-loop helicity amplitude calculations for $gg o Zg$ and $gg o Z\gamma$, advancing precision in QCD predictions for these processes.

Findings

Provides explicit two-loop helicity amplitudes for $gg o Zg$ and $gg o Z\gamma$.

Enables more accurate NLO predictions for Z+jet and Zγ production.

Supports precision tests of the Standard Model at colliders.

Abstract

We compute the helicity amplitudes for the processes $gg\to Zg$ and $gg\to Z\gamma$ to two loops in massless QCD. The perturbative expansion of these processes starts only at the one-loop level, such that our results are a crucial ingredient to the NLO corrections to $Z\gamma$ and $Z+$jet production through gluon fusion.