Matching matrix elements and shower evolution for top-pair production in hadronic collisions

Mangano, M.; Moretti, M.; Piccinini, F.; Treccani, M.

doi:10.1088/1126-6708/2007/01/013

Cited by 633 publications

(609 citation statements)

References 23 publications

(21 reference statements)

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“…All of the parton level signal and the background events are showered using Pythia6.4 [67]. The MLM matching scheme [68] is used to avoid double counting. Detector effects are mimicked with PGS4 [69].…”

Section: Hh Channelmentioning

confidence: 99%

Higgs-flavon mixing and LHC phenomenology in a simplified model of broken flavor symmetry

et al. 2014

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The LHC phenomenology of a low-scale gauged flavor symmetry model with inverted hierarchy is studied, through introduction of a simplified model of broken flavor symmetry. A new scalar (a flavon) and a new neutral top-philic massive gauge boson emerge with mass in the TeV range along with a new heavy fermion associated with the standard model top quark. After checking constraints from electroweak precision observables, we investigate the influence of the model on Higgs boson physics, notably on its production cross section and decay branching fractions. Limits on the flavon ϕ from heavy Higgs boson searches at the LHC at 7 and 8 TeV are presented. The branching fractions of the flavon are computed as a function of the flavon mass and the Higgs-flavon mixing angle. We also explore possible discovery of the flavon at 14 TeV, particularly via the ϕ → Z 0 Z 0 decay channel in the 2 2 final state, and through standard model Higgs boson pair production ϕ → hh in the bbγγ final state. We conclude that the flavon mass range up to 500 GeV could probed down to quite small values of the Higgs-flavon mixing angle with 100 fb −1 of integrated luminosity at 14 TeV.

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Section: Hh Channelmentioning

confidence: 99%

Higgs-flavon mixing and LHC phenomenology in a simplified model of broken flavor symmetry

et al. 2014

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“…The MC@NLO+HERWIG predictions underestimate the cross-section for six jets in the tt final state. The underestimate of the higher jet multiplicity bins for MC@NLO compared to ALPGEN is also observed in [13], where the difference is explained by a significantly smaller contribution of the tt + q(g) hard matrix-element calculation to the multijet finalstates and a higher fraction of additional jets from the parton shower [13].In contrast to MC@NLO, the prediction from POWHEG+PYTHIA is in reasonable agreement with the data for all jet p T thresholds and jet multiplicities. POWHEG(h damp ) +PYTHIA provides the best description of the leading-jet p T and the higher jet multiplicities.…”

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confidence: 55%

Section: Resultsmentioning

confidence: 85%

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Measurement of the t t ¯ $$ t\overline{t} $$ production cross-section as a function of jet multiplicity and jet transverse momentum in 7 TeV proton-proton collisions with the ATLAS detector

Aad

2015

J. High Energ. Phys.

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The tt production cross-section dependence on jet multiplicity and jet transverse momentum is reported for proton-proton collisions at a centre-of-mass energy of 7 TeV in the single-lepton channel. The data were collected with the ATLAS detector at the CERN Large Hadron Collider and comprise the full 2011 data sample corresponding to an integrated luminosity of 4.6 fb −1 . Differential cross-sections are presented as a function of the jet multiplicity for up to eight jets using jet transverse momentum thresholds of 25, 40, 60, and 80 GeV, and as a function of jet transverse momentum up to the fifth jet. The results are shown after background subtraction and corrections for all known detector effects, within a kinematic range closely matched to the experimental acceptance. Several QCD-based Monte Carlo models are compared with the results. Sensitivity to the parton shower modelling is found at the higher jet multiplicities, at high transverse momentum of the leading jet and in the transverse momentum spectrum of the fifth leading jet. The MC@NLO+HERWIG MC is found to predict too few events at higher jet multiplicities. Keywords: Hadron-Hadron ScatteringArXiv ePrint: 1407.0891Open Access, Copyright CERN, for the benefit of the ATLAS Collaboration. Article funded by SCOAP 3 .doi:10.1007/JHEP01(2015)020 Tables of results with systematic uncertainties 38 The ATLAS collaboration 51 JHEP01(2015)020 IntroductionFinal states of proton-proton (pp) collisions at the Large Hadron Collider (LHC) [1] often include jets arising from QCD bremsstrahlung due to the strongly interacting partons in the initial state and the high centre-of-mass energy of the scattering process that allows for radiation in a large kinematic phase space. In this paper, an inclusive measurement of jets in top-antitop (tt) final states is presented, which is sensitive to the production mechanism -1 - JHEP01(2015)020of additional jets in these events. The events studied have a high partonic-system centreof-mass energy and are complex final states consisting of several coloured partons, with sensitivity to various hard scales. The production of additional jets in tt events is sensitive to higher-order perturbative QCD effects. The uncertainties associated with these processes are a significant source of uncertainty in precision measurements, such as the measurement of the top-quark mass [2] or the inclusive tt production cross-section at the LHC [18]. Several theoretical approaches are available to model tt processes, including NLO QCD calculations, parton-shower models and methods matching fixed-order QCD with the parton shower. The aim of this paper is to test these theoretical approaches by making a direct measurement of jet activity in tt events. Furthermore, tt production with additional jets is a dominant background in certain Higgs boson production processes and decay modes and to many searches for new physics phenomena [3,4].Tests similar to those presented in this paper have been performed at lower energies, using measurements of je...

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“…To run Alpgen we use 4.0 as the maximum pseudorapidity and 0.6 as the minimum jet separation. See [18] for a comparison of Alpgen and MC@NLO and for a description of the MLM matching procedure used by Alpgen.…”

Section: Jhep03(2007)063mentioning

confidence: 99%

t′ at the LHC: the physics of discovery

Holdom¹

2007

J. High Energy Phys.

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A search for a fourth family at the LHC is presently a low priority, but we argue that an effective search can be conducted early with only a few inverse femtobarns of data. We discuss a method based on invariant masses of single jets for identifying the W 's originating from heavy quark decays. This can significantly increase signal to background in the reconstruction of the t mass. We also study the various types of physics that can impact the background estimate, most notably higher order effects, initial state radiation, and models of the underlying event.

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Matching matrix elements and shower evolution for top-pair production in hadronic collisions

Cited by 633 publications

References 23 publications

Higgs-flavon mixing and LHC phenomenology in a simplified model of broken flavor symmetry

Higgs-flavon mixing and LHC phenomenology in a simplified model of broken flavor symmetry

Measurement of the t t ¯ $$ t\overline{t} $$ production cross-section as a function of jet multiplicity and jet transverse momentum in 7 TeV proton-proton collisions with the ATLAS detector

t′ at the LHC: the physics of discovery

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