Four-lepton production in gluon fusion at NLO matched to parton showers

TL;DR

This paper calculates NLO QCD corrections to gluon-induced ZZ and WW production, matched with parton showers, enabling more precise simulations of diboson and offshell Higgs processes in experiments.

Contribution

It introduces a NLO QCD calculation for gluon-induced diboson production matched with parton showers, including interference effects and offshell contributions.

Findings

Parton-shower effects are marginal in inclusive observables.

Significant effects observed in exclusive jet observables.

The Monte Carlo generator facilitates realistic experimental simulations.

Abstract

We present a calculation of the next-to-leading order (NLO) QCD corrections to gluon-induced electroweak gauge boson pair production, $gg \to ZZ$ and $gg \to W^+W^-$, matched to the PYTHIA8 parton shower in the POWHEG approach. The calculation consistently incorporates the continuum background, the Higgs-mediated $gg\to H^* \to VV$ process, and their interference. We consider leptonic decay modes of the massive vector bosons and retain offshell and non-resonant contributions. The processes considered are loop-induced at leading order and thus contain two-loop virtual contributions as well as loop-squared real contributions. Parton-shower effects are found to be marginal in inclusive observables and quite sizeable in observables that are exclusive in additional jet radiation. The Monte Carlo generator presented here allows for realistic experimental effects to be incorporated in state-of-the-art precision analyses of diboson production and of the Higgs boson in the offshell regime.