QCD corrections to vector boson pair production in gluon fusion including interference effects with off-shell Higgs at the LHC

Abstract

Abstract:We compute next-to-leading order (NLO) QCD corrections to the production of two massive electroweak bosons in gluon fusion. We consider both the prompt production process gg → V V and the production mediated by an exchange of an s-channel Higgs boson, gg → H * → V V . We include final states with both on-and off-shell vector bosons with leptonic decays. The gluonic production of vector bosons is a loop-induced process, including both massless and massive quarks in the loop. For gg → ZZ production, we obtain the NLO QCD corrections to the massive loops through an expansion around the heavy top limit. This approximation is valid below the top production threshold, giving a broad range of invariant masses between the Higgs production and the top production thresholds in which our results are valid. We explore the NLO QCD effects in gg → ZZ focusing, in particular, on the interference between prompt and Higgs-mediated processes. We find that the QCD corrections to the interference are large and similar in size to the corrections to both the signal and the background processes. At the same time, we observe that corrections to the interference change rapidly with the four-lepton invariant mass in the region around the ZZ production threshold. We also study the interference effects in gg → W + W − production where, due to technical limitations, we only consider contributions of massless loops. We find that the QCD corrections to the interference in this case are somewhat larger than those for either the signal or the background.

ZZ production in gluon fusion at NLO matched to parton shower

“…In this study we have primarily concentrated on the ZZ-production process as a signal and have consequently not attempted to include either the Higgs-boson mediated channel or the interference between the two production modes. These effects are known to be important and severely affect the production rates mostly around the Higgs-boson resonant region and for large values of m 4l [32][33][34]. The proper inclusion of all the aforementioned effects in a NLO calculation matched to parton shower will be the subject of a separate investigation.…”

“…Refs. [33,34] and [32]). The fixed-order computation is performed using the same strategy presented in Ref.…”

NNLO QCD + NLO EW with Matrix+OpenLoops: precise predictions for vector-boson pair production

“…The contribution of this gg → V V channel to chargeneutral final states is quite sizeable. It has been computed to one order higher in perturbation theory [30,32,[80][81][82][83][84], which is assumed to be the dominant O(α 3 S ) correction to these processes. In the combination of NNLO QCD and NLO EW corrections presented in this paper, the gg → V V channels are included at O(α 2 S ) as part of the NNLO QCD corrections, i.e.…”

Measurement of the four-lepton invariant mass spectrum in 13 TeV proton-proton collisions with the ATLAS detector

“…This sample includes the box diagram, the s-channel process proceeding via a Higgs boson, and the interference between the two. Recently, a NLO QCD calculation for the three components became available [44,45] allowing m 4 differential K-factors to be calculated with the 1/m t expansion below 2m t , and assuming a massless quark approximation above this threshold. This NLO QCD calculation was used to correct the s-channel process gg → H * → Z Z ( * ) → 4 , the box diagram gg → 4 and the interference with separate K-factors.…”