ZZ+jet production via gluon fusion at the LHC

TL;DR

This paper calculates the gluon-fusion contribution to Z+jet production at the LHC, showing it can significantly impact background estimates for Higgs and new physics searches, especially due to large gluon flux.

Contribution

It provides a detailed calculation of the loop-induced gg > ZZg process, including complex pentagon integrals, highlighting its importance in LHC analyses.

Findings

Gluon-fusion contributes over 10% to NLO results.

Increases overall scale uncertainty.

Large interference effects off-shell Higgs.

Abstract

Pair production of Z bosons in association with a hard jet is an important background for Higgs particle or new physics searches at the LHC. The loop-induced gluon-fusion process gg > ZZg contributes formally only at the next-to-next-to-leading order. Nevertheless, it can get enhanced by the large gluon flux at the LHC, and thus should be taken into account in relevant experimental searches. We provide the details and results of this calculation, which involves the manipulation of rank-5 pentagon integrals. Our results show that the gluon-fusion process can contribute more than 10% to the next-to-leading order QCD result and increases the overall scale uncertainty. Moreover, interference effects between Higgs and non-Higgs contributions can become large in phase-space regions where the Higgs is far off-shell.