Abstract
We present a calculation of the next-to-leading order (NLO) QCD corrections to the hadroproduction process $gg\to ZZ \to e^+e^- \mu^+ \mu^-$, matched to the parton shower in the POWHEG framework. We take advantage of the POWHEG BOX tool for the implementation and rely on PYTHIA 8 for the showering and hadronization stages. We fully include $\gamma^*/Z$ interference effects, while also covering the single-resonant region. For this phenomenological study we focus on four lepton production as a signal process, neglecting all quark mass effects as well as the Higgs-mediated contributions, which are known to be subdominant in this case. We provide predictions from our simulations for the 13 TeV LHC Run II setup, including realistic experimental cuts.
Highlights
During the Run I of the Large Hadron Collider (LHC), the production of a pair of vector bosons was one of the processes studied in greatest detail [1,2,3,4,5,6]
We present results for the next-to-leading order (NLO) QCD corrections to ZZ production in the gluon fusion channel matched to parton shower within the POWHEG framework
We include results at the so-called Les Houches event (LHE) level, i.e. after the first hard emission generated with the POWHEG method
Summary
During the Run I of the Large Hadron Collider (LHC), the production of a pair of vector bosons was one of the processes studied in greatest detail [1,2,3,4,5,6]. The leading order (LO) contribution to the gg channel is given by a one-loop amplitude and first enters the overall diboson production rate at Oðα2sÞ, i.e. at NNLO. It has been known for some time that these contributions increase the cross section by approximately 5%–15%, enhanced by the large gluonic flux [27,28,29]. There it was shown that the next-to-leading order (NLO) corrections further enhance the production rate, resulting in an overall increase of the predictions for ZZ production at the level of ∼5% This exceeds the scale variation uncertainty of the NNLO computation, making its inclusion important for precision phenomenology.
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