Abstract
The data taken in Run II at the Large Hadron Collider have started to probe Higgs boson production at high transverse momentum. Future data will provide a large sample of events with boosted Higgs boson topologies, allowing for a detailed understanding of electroweak Higgs boson plus two-jet production, and in particular the vector-boson fusion mode (VBF). We perform a detailed comparison of precision calculations for Higgs boson production in this channel, with particular emphasis on large Higgs boson transverse momenta, and on the jet radius dependence of the cross section. We study fixed-order predictions at next-to-leading order and next-to-next-to-leading order QCD, and compare the results to NLO plus parton shower (NLOPS) matched calculations. The impact of the NNLO corrections on the central predictions is mild, with inclusive scale uncertainties of the order of a few percent, which can increase with the imposition of kinematic cuts. We find good agreement between the fixed-order and matched calculations in non-Sudakov regions, and the various NLOPS predictions also agree well in the Sudakov regime. We analyze backgrounds to VBF Higgs boson production stemming from associated production, and from gluon-gluon fusion. At high Higgs boson transverse momenta, the ∆yjj and/or mjj cuts typically used to enhance the VBF signal over background lead to a reduced efficiency. We examine this effect as a function of the jet radius and using different definitions of the tagging jets. QCD radiative corrections increase for all Higgs production modes with increasing Higgs boson pT, but the proportionately larger increase in the gluon fusion channel results in a decrease of the gluon-gluon fusion background to electroweak Higgs plus two jet production upon requiring exclusive two-jet topologies. We study this effect in detail and contrast in particular a central jet veto with a global jet multiplicity requirement.
Highlights
To interpret the upcoming precise measurements in various fiducial regions, theory predictions of the Higgs-plus-two-jet final states need to be performed with the highest available accuracy for all relevant production channels
We will explore the robustness of the theoretical predictions in the high pT vector-boson fusion (VBF) region by comparing fixed-order results at next-to-leading order (NLO) and next-to-next-to-leading order (NNLO) with NLO predictions matched to parton showers (NLOPS), with a particular emphasis on the dependence of the cross sections on the jet radius
To have an “effective” POWHEG BOX NLO plus parton shower (NLOPS) generator for VH with hadronic decay, it is sufficient to include the contribution in eq (2.7) in the weight of the event, which must be showered with a parton shower that implements matrix element corrections: in this way, the event weight is identical to the NLO cross section differential in the undelying Born kinematics and the hardest emission from the production process and from the V decay is described using the exact matrix element
Summary
Parton level fixed-order predictions for the VBF channel are calculated using the NNLOjet package, including QCD corrections up to NNLO [22] in the structure function approximation [18], i.e. omitting non-factorizable corrections at NLO and at NNLO. With an independent calculation [21] of VBF at NNLO QCD, which employed the same approximations. A recent study [28] using the eikonal approximation estimates the nonfactorizable corrections to be less than 2% (with respect to LO) for differential observables. NNLOjet provides predictions for the gluon-gluon fusion production channel and is used to compute the histogram-based reweighting factors needed to include approximate top-quark mass effects in the NLO matched results
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