ATLAS reports an 8+ sigma excess in ttbar production near threshold, consistent with NRQCD quasi-bound states and measuring 9.3 pb.
Ježo, J.M
5 Pith papers cite this work. Polarity classification is still indexing.
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Pith papers citing it
abstract
The increasingly high accuracy of top-quark studies at the LHC calls for a theoretical description of $t\bar t$ production and decay in terms of exact matrix elements for the full $2\to 6$ process that includes the off-shell production and the chain decays of $t\bar t$ and $tW$ intermediate states, together with their quantum interference. Corresponding NLO QCD calculations matched to parton showers are available for the case of dileptonic channels and are implemented in the bb4l Monte Carlo generator, which is based on the resonance-aware POWHEG method. In this paper, we present the first NLOPS predictions of this kind for the case of semileptonic channels. In this context, the interplay of off-shell $t\bar t+tW$ production with various other QCD and electroweak subprocesses that yield the same semileptonic final state is discussed in detail. On the technical side, we improve the resonance-aware POWHEG procedure by means of new resonance histories based on matrix elements, which enable a realistic separation of $t\bar t$ and $tW$ contributions. Moreover, we introduce a general approach which makes it possible to avoid certain spurious terms that arise from the perturbative expansion of decay widths in any off-shell higher-order calculation, and which are large enough to jeopardise physical finite-width effects. These methods are implemented in a new version of the bb4l Monte Carlo generator, which is applicable to all dileptonic and semileptonic channels, and can be extended to fully hadronic channels. The presented results include a NLOPS comparison of off-shell against on-shell $t\bar t+tW$ production and decay, where we highlight various non-trivial aspects related to NLO and parton-shower radiation in leptonic and hadronic top decays.
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representative citing papers
First complete NLO QCD+EW predictions for off-shell ttbar production in the lepton+jets channel, including all subleading Born and NLO terms and an IR-safe photon-jet treatment, at 13.6 TeV.
First automated MC@NLO matching of NLO QCD+EW to an interleaved QCD+QED parton shower with resonance-aware dipole subtraction, validated for Drell-Yan lepton-pair production.
A resonance- and width-aware parton shower with NLO matching is developed for e+e- to W+W- bbbar, extending beyond standard Breit-Wigner approximations, with a public SHERPA-based simulator.
Near-threshold top-quark pair production cross section at 13 TeV LHC is 11.67 pb with +1.43/-1.47 pb uncertainty, including NRQCD Green's function effects and comparison to POWHEG-BOX.
citing papers explorer
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Observation of a cross-section enhancement near the $t\bar{t}$ production threshold in $\sqrt{s}=13$ TeV $pp$ collisions with the ATLAS detector
ATLAS reports an 8+ sigma excess in ttbar production near threshold, consistent with NRQCD quasi-bound states and measuring 9.3 pb.
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Complete NLO corrections to off-shell $\boldsymbol{t\bar{t}}$ production in the $\boldsymbol{\ell+j}$ decay channel
First complete NLO QCD+EW predictions for off-shell ttbar production in the lepton+jets channel, including all subleading Born and NLO terms and an IR-safe photon-jet treatment, at 13.6 TeV.
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A resonance-aware MC@NLO QCD+EW-matched calculation of lepton-pair production
First automated MC@NLO matching of NLO QCD+EW to an interleaved QCD+QED parton shower with resonance-aware dipole subtraction, validated for Drell-Yan lepton-pair production.
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Resonance- and Width-aware Parton Shower Evolution and NLO Matching
A resonance- and width-aware parton shower with NLO matching is developed for e+e- to W+W- bbbar, extending beyond standard Breit-Wigner approximations, with a public SHERPA-based simulator.
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Threshold Top-Quark Pair-Production: Cross Sections and Key Uncertainties
Near-threshold top-quark pair production cross section at 13 TeV LHC is 11.67 pb with +1.43/-1.47 pb uncertainty, including NRQCD Green's function effects and comparison to POWHEG-BOX.