Precise Higgs-background predictions: merging NLO QCD and squared quark-loop corrections to four-lepton + 0,1 jet production

• Published in: The journal of high energy physics 2014, Vol.2014 (1), p.1-45, Article 46
• Main Authors: Cascioli, F., Höche, S., Krauss, F., Maierhöfer, P., Pozzorini, S., Siegert, F.
• Format: Article
• Language: English
• Subjects: Bins; Channels; Classical and Quantum Gravitation; Elementary Particles; High energy physics; Mathematical analysis; Merging; Partons; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Relativity Theory; Showers; String Theory; Uncertainty
• ISSN: 1029-8479; 1029-8479
• DOI: 10.1007/JHEP01(2014)046

A bstract We present precise predictions for four-lepton plus jets production at the LHC obtained within the fully automated S herpa + O pen L oops framework. Off-shell intermediate vector bosons and related interferences are consistently included using the complex-mass scheme. Four-lepton plus 0- and 1-jet final states are described at NLO accuracy, and the precision of the simulation is further increased by squared quark-loop NNLO contributions in the gg → 4 ℓ , gg → 4 ℓ + g, g q → 4 ℓ + q , and → 4 ℓ + g channels. These NLO and NNLO contributions are matched to the S herpa parton shower, and the 0- and 1-jet final states are consistently merged using the M eps @N lo technique. Thanks to Sudakov resummation, the parton shower provides improved predictions and uncertainty estimates for exclusive observables. This is important when jet vetoes or jet bins are used to separate four-lepton final states arising from Higgs decays, diboson production, and top-pair production. Detailed predictions are presented for the Atlas and C ms H → WW * analyses at 8 TeV in the 0- and 1-jet bins. Assessing renormalisation-, factorisation- and resummationscale uncertainties, which reflect also unknown subleading Sudakov logarithms in jet bins, we find that residual perturbative uncertainties are as small as a few percent.