NNLO corrections to top-pair production at hadron colliders: the all-fermionic scattering channels

Czakon, M.; Mitov, Alexander

doi:10.1007/jhep12(2012)054

Cited by 448 publications

(375 citation statements)

References 87 publications

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“…In Table I the observed yields in data are compared to the expected background and the tt signal normalized to σ tt ¼ 177 þ10 −11 pb calculated at NNLO in QCD including resummation of next-to-next-to-leading logarithmic soft gluon terms [63][64][65][66][67] with TOP++ v2.0 [68] for a top quark mass of 172.5 GeV. A significantly lower yield in the dielectron channel compared to the dimuon channel is due to the stringent isolation criteria and higher p T cut on the electrons.…”

Section: A Dilepton Channelmentioning

confidence: 99%

Measurements of spin correlation in top-antitop quark events from proton-proton collisions ats=7 TeVusing the ATLAS detector

Aad¹,

Abbott²,

Abdallah³

et al. 2014

Phys. Rev. D

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Measurements of spin correlation in top quark pair production are presented using data collected with the ATLAS detector at the LHC with proton-proton collisions at a center-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 4.6 fb −1 . Events are selected in final states with two charged leptons and at least two jets and in final states with one charged lepton and at least four jets. Four different observables sensitive to different properties of the top quark pair production mechanism are used to extract the correlation between the top and antitop quark spins. Some of these observables are measured for the first time. The measurements are in good agreement with the Standard Model prediction at next-to-leadingorder accuracy.

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Section: A Dilepton Channelmentioning

confidence: 99%

Measurements of spin correlation in top-antitop quark events from proton-proton collisions ats=7 TeVusing the ATLAS detector

Aad¹,

Abbott²,

Abdallah³

et al. 2014

Phys. Rev. D

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“…This calculation was carried out at next-to-next-to-leading order (NNLO) in QCD including resummation of next-to-next-toleading logarithmic (NNLL) soft gluon terms [43][44][45][46][47] with Top++2.0 [48]. The PDF and α S uncertainties were calculated using the PDF4LHC prescription [49] with the MSTW2008 68CL NNLO [50,51], CT10 NNLO [36,52] and NNPDF2.3 5f FFN [53] PDF sets, and added in quadrature to the scale uncertainty.…”

Section: Jhep01(2015)020mentioning

confidence: 99%

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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Section: Jhep08(2014)103mentioning

confidence: 99%

“…Modelling uncertainties are assessed using events generated with Alpgen 2.14, using the CTEQ6L1 [37] PDF set and interfaced to Herwig 6.5.20 [41] for parton showers and hadronisation. The tt cross-section is normalised to 253 +13 −15 pb, calculated at NNLO in QCD including resummation of next-to-next-to-leading logarithmic (NNLL) soft gluon terms with Top++ 2.0 [42][43][44][45][46][47].Samples are generated separately for each of the three single-top production modes: s-channel, t-channel and W t-channel. For the s-and W t-channel, events are generated with MC@NLO 4.06 [48], interfaced to Herwig++ 2.6.3 [49] for parton showering and hadronisation.…”

mentioning

confidence: 99%

Search for microscopic black holes and string balls in final states with leptons and jets with the ATLAS detector at s $$ \sqrt{s} $$ = 8 TeV

Aad¹,

Abbott²,

Abdallah³

et al. 2014

J. High Energ. Phys.

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A search for an excess of events with multiple high transverse momentum objects including charged leptons and jets is presented, using 20.3 fb −1 of proton-proton collision data recorded by the ATLAS detector at the Large Hadron Collider in 2012 at a centre-of-mass energy of √ s = 8 TeV. No excess of events beyond Standard Model expectations is observed. Using extra-dimensional models for black hole and string ball production and decay, exclusion contours are determined as a function of the mass threshold for production and the fundamental gravity scale for two, four and six extra dimensions. For six extra dimensions, mass thresholds of 4.8-6.2 TeV are excluded at 95% confidence level, depending on the fundamental gravity scale and model assumptions. Upper limits on the fiducial cross-sections for non-Standard Model production of these final states are set. 6 Event selection 8 7 Background estimation 9 7.1 Prompt background estimation from control regions 9 7.2 Backgrounds from misidentified objects and non-prompt leptons 13 7.3 Background smoothing with fits 148 Systematic uncertainties 159 Results and interpretation 17 Summary 25The ATLAS collaboration 32 IntroductionA long-standing problem in particle physics is the very large difference between two apparently fundamental energy scales: the electroweak scale at O(0.1 TeV) and the gravitational (Planck) scale M Pl = O(10 16 TeV). Models postulating extra spatial dimensions into which the gravitational field propagates attempt to address this hierarchy problem [1][2][3][4]. In most of these models, the Standard Model (SM) fields are constrained to the one time and three spatial dimensions of our universe, whilst the gravitons also propagate into the n "bulk" extra dimensions. In these models, the fundamental gravitational scale in the full (n + 4) space-time dimensions, M D , is dramatically lower than M Pl , and represents an effective scale appropriate for probes of the gravitational interactions at low energies. A value of M D in the TeV range would allow for the production of strong gravitational states such as microscopic black holes at energies accessible at the Large Hadron Collider (LHC) [5][6][7]. Two well-motivated extra-dimensional models are those with large flat extra dimensions -1 - JHEP08(2014)103(ADD models [2,3]) and those with small, usually warped, extra dimensions (RS models [4]). This analysis considers ADD models, for which the n = 1 case is ruled out and the n = 2 case is disfavoured by current astrophysical and tabletop experiments [8]. Thus, benchmark models with two, four and six additional spatial dimensions are considered.Estimates of the black hole production cross-sections invoke semiclassical approximations, the validity of which require the production centre-of-mass energy to be significantly above M D . This motivates the introduction of a production mass threshold M th , well above M D . In the black hole formation stage, some energy is expected to be lost to gravitational or SM radiation. This has recently been calcu...

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NNLO corrections to top-pair production at hadron colliders: the all-fermionic scattering channels

Cited by 448 publications

References 87 publications

Measurements of spin correlation in top-antitop quark events from proton-proton collisions ats=7 TeVusing the ATLAS detector

Measurements of spin correlation in top-antitop quark events from proton-proton collisions ats=7 TeVusing the ATLAS detector

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

Search for microscopic black holes and string balls in final states with leptons and jets with the ATLAS detector at s $$ \sqrt{s} $$ = 8 TeV

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