NLO QCD predictions for $t\bar{t}b\bar{b}$ production in association with a light jet at the LHC

Abstract

Theoretical predictions for ttbb production are of crucial importance for ttH measurements in the H->bb channel at the LHC. To address the large uncertainties associated with the modelling of extra QCD radiation in ttbb events, in this paper we present a calculation of pp->ttbbj at NLO QCD. The behaviour of NLO corrections is analysed in a variety of observables, and to assess theoretical uncertainties we use factor-two rescalings as well as different dynamic scales. In this context, we propose a systematic alignment of dynamic scales that makes it possible to disentangle normalisation and shape uncertainties in a transparent way. Scale uncertainties at NLO are typically at the level of 20-30% in fiducial cross sections, and below 10% for the shapes of distributions. The kinematics of QCD radiation is investigated in detail, including the effects of its recoil on the objects of the ttbb system. In particular, we discuss various azimuthal correlations that allow one to charaterise the QCD recoil pattern in a precise and transparent way. In general, the calculation at hand provides a variety of precise benchmarks that can be used to validate the modelling of QCD radiation in ttbb generators. Moreover, as we will argue, pp->ttbbj at NLO entails information that can be used to gain insights into the perturbative convergence of the inclusive ttbb cross section beyond NLO. Based on this idea, we address the issue of the large NLO K-factor observed in the ttbb cross section, and we provide evidence that supports the reduction of this K-factor through a mild adjustment of the QCD scales that are conventionally used for this process. The presented 2->5 NLO calculations have been carried out using OpenLoops 2 in combination with Sherpa and Munich.

arXiv comment37 pages, 18 figures, 6 tables

References in corpus (36)

• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• The anti-k_t jet clustering algorithm
• FastJet user manual
• Parton distributions for the LHC Run II
• Event generation with SHERPA 1.1
• LHAPDF6: parton density access in the LHC precision era
• A General Algorithm for Calculating Jet Cross Sections in NLO QCD
• Scattering Amplitudes with Open Loops
• Herwig 7.0 / Herwig++ 3.0 Release Note
• Comix, a new matrix element generator
• Collier: a fortran-based Complex One-Loop LIbrary in Extended Regularizations
• Reducing full one-loop amplitudes to scalar integrals at the integrand level
• The Dipole Formalism for Next-to-Leading Order QCD Calculations with Massive Partons
• Rivet user manual
• Reduction schemes for one-loop tensor integrals
• OpenLoops 2
• CutTools: a program implementing the OPP reduction method to compute one-loop amplitudes
• OneLOop: for the evaluation of one-loop scalar functions
• AMEGIC++ 1.0, A Matrix Element Generator In C++
• Fully differential NNLO computations with MATRIX
• Reduction of one-loop tensor 5-point integrals
• Assault on the NLO Wishlist: pp -> tt bb
• Scalar one-loop 4-point integrals
• RECOLA: REcursive Computation of One-Loop Amplitudes
• Automating dipole subtraction for QCD NLO calculations
• Recola2: REcursive Computation of One-Loop Amplitudes 2
• NLO QCD corrections to pp -> t anti-t b anti-b + X at the LHC
• NLO QCD corrections to top anti-top bottom anti-bottom production at the LHC: 2. full hadronic results
• On-the-fly reduction of open loops
• Top-quark pair hadroproduction at next-to-next-to-leading order in QCD
• Top-quark pair production at the LHC: Fully differential QCD predictions at NNLO
• Color-dressed recursive relations for multi-parton amplitudes
• NLO matching for ttbb production with massive b-quarks
• New NLOPS predictions for $\mathbf{t}\bar{\mathbf{t}}+\mathbf{b}$-jet production at the LHC
• A unified NLO description of top-pair and associated Wt production
• Hadroproduction of $t\bar{t}b\bar{b}$ final states at LHC: predictions at NLO accuracy matched with Parton Shower

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