Measurement Of The Integrated And Differential Tt U00af Production Cross Sections For High Pt Top Quarks In Pp Collisions At S
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Measurement Of The Integrated And Differential Tt U00af Production Cross Sections For High Pt Top Quarks In Pp Collisions At S
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Author :
language : en
Publisher:
Release Date : 2016
Measurement Of The Integrated And Differential Tt U00af Production Cross Sections For High Pt Top Quarks In Pp Collisions At S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
The cross section for pair production of top quarks ($tar{t}$) with high transverse momenta is measured in pp collisions, collected with the CMS detector at the LHC with √s=8 TeV in data corresponding to an integrated luminosity of 19.7 fb-1. The measurement is performed using lepton+jets events, where one top quark decays semileptonically, while the second top quark decays to a hadronic final state. The hadronic decay is reconstructed as a single, large-radius jet, and identified as a top quark candidate using jet substructure techniques. The integrated cross section and the differential cross sections as a function of top quark pT and rapidity are measured at particle level within a fiducial region related to the detector-level requirements and at parton level. The particle-level integrated cross section is found to be ?$tar{t}$ = 0.499 ± 0.035(stat+syst) ± 0.095(theo) ± 0.013(lumi) pb for top quark pT > 400 GeV. The parton-level measurement is ?$tar{t}$ = 1.44 ± 0.10(stat+syst) ± 0.29(theo) ± 0.04(lumi) pb. Lastly, the integrated and differential cross section results are compared to predictions from several event generators.
Measurement Of The Integrated And Differential T Tbar Production Cross Sections For High Pt Top Quarks In Pp Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2016
Measurement Of The Integrated And Differential T Tbar Production Cross Sections For High Pt Top Quarks In Pp Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
The cross section for pair production of top quarks (t-tbar) with high transverse momenta is measured in pp collisions, collected with the CMS detector at the LHC with sqrt(s) = 8 TeV in data corresponding to an integrated luminosity of 19.7 inverse-femtobarns. The measurement is performed using lepton+jets events, where one top quark decays semileptonically, while the second top quark decays to a hadronic final state. The hadronic decay is reconstructed as a single, large-radius jet, and identified as a top quark candidate using jet substructure techniques. The integrated cross section and the differential cross sections as a function of top quark pt and rapidity are measured at particle level within a fiducial region related to the detector-level requirements and at parton level. The particle-level integrated cross section is found to be sigma[t-tbar] = 0.499 +/- 0.035 (stat+syst) +/- 0.095 (theory) +/- 0.013 (lumi) pb for top quark pt> 400 GeV. The parton-level measurement is sigma[t-tbar] = 1.44 +/- 0.10 (stat+syst) +/- 0.29 (theory) +/- 0.04 (lumi) pb. The integrated and differential cross section results are compared to predictions from several event generators.
Measurements Of Normalized Differential Cross Sections For Tt U00af Production In Pp Collisions At S
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Author :
language : en
Publisher:
Release Date : 2014
Measurements Of Normalized Differential Cross Sections For Tt U00af Production In Pp Collisions At S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
We present measurements of normalized differential cross sections for top-quark pair production as a function of the top-quark transverse momentum, and of the mass, transverse momentum, and rapidity of the t¯t system, in proton–proton collisions at a center-of-mass energy of √ s=7 TeV. The data set corresponds to an integrated luminosity of 4.6 fb−1, recorded in 2011 with the ATLAS detector at the CERN Large Hadron Collider. Events are selected in the lepton + jets channel, requiring exactly one lepton and at least four jets with at least one of the jets tagged as originating from a b-quark. The measured spectra are corrected for detector efficiency and resolution effects and are compared to several Monte Carlo simulations and theory calculations. The results are in fair agreement with the predictions in a wide kinematic range. Nevertheless, data distributions are softer than predicted for higher values of the mass of the t¯t system and of the top-quark transverse momentum. Lastly, the measurements can also discriminate among different sets of parton distribution functions.
Simultaneous Measurements Of The Tt U00af W W And Z U2192 Production Cross Sections In Pp Collisions At S
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language : en
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Release Date : 2015
Simultaneous Measurements Of The Tt U00af W W And Z U2192 Production Cross Sections In Pp Collisions At S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
Simultaneous measurements of the tt¯, W+W–, and Z/?*→?? production cross-sections using an integrated luminosity of 4.6 fb–1 of pp collisions at √s=7 TeV collected by the ATLAS detector at the LHC are presented. Events are selected with two high transverse momentum leptons consisting of an oppositely charged electron and muon pair. The three processes are separated using the distributions of the missing transverse momentum of events with zero and greater than zero jet multiplicities. Measurements of the fiducial cross-section are presented along with results that quantify for the first time the underlying correlations in the predicted and measured cross-sections due to proton parton distribution functions. Results indicate that the correlated next-to-leading-order predictions for tt¯ and Z/?*→?? underestimate the data, while those at next-to-next-to-leading-order generally describe the data well. The full cross-sections are measured to be ?(tt¯)=181.2 ± 2.8+9.7–9.5 ± 3.3 ± 3.3 pb, ?(W+W–) = 53.3 ± 2.7+7.3–8.0 ± 1.0 ± 0.5 pb, and ?(Z/?*→??) = 1174 ± 24+72–87 ± 21 ± 9 pb, where the cited uncertainties are due to statistics, systematic effects, luminosity and the LHC beam energy measurement, respectively. The W+W– measurement includes the small contribution from Higgs boson decays, H → W+W–.
Measurement Of Double Differential Cross Sections For Top Quark Pair Production In Pp Collisions At Sqrt S
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Author :
language : en
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Release Date : 2017
Measurement Of Double Differential Cross Sections For Top Quark Pair Production In Pp Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
Normalized double-differential cross sections for top quark pair (ttbar) production are measured in pp collisions at a centre-of-mass energy of 8 TeV with the CMS experiment at the LHC. The analyzed data correspond to an integrated luminosity of 19.7 inverse femtobarns. The measurement is performed in the dilepton e+/- mu-/+ final state. The ttbar cross section is determined as a function of various pairs of observables characterizing the kinematics of the top quark and ttbar system. The data are compared to calculations using perturbative quantum chromodynamics at next-to-leading and approximate next-to-next-to-leading orders. They are also compared to predictions of Monte Carlo event generators that complement fixed-order computations with parton showers, hadronization, and multiple-parton interactions. Overall agreement is observed with the predictions, which is improved when the latest global sets of proton parton distribution functions are used. The inclusion of the measured ttbar cross sections in a fit of parametrized parton distribution functions is shown to have significant impact on the gluon distribution.
Measurement Of The Differential Cross Sections For Top Quark Pair Production As A Function Of Kinematic Event Variables In Pp Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2016
Measurement Of The Differential Cross Sections For Top Quark Pair Production As A Function Of Kinematic Event Variables In Pp Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
Measurements are reported of the normalized differential cross sections for top quark pair production with respect to four kinematic event variables: the missing transverse energy; the scalar sum of the jet transverse momentum (pT); the scalar sum of the pT of all objects in the event; and the pT of leptonically decaying W bosons from top quark decays. The data sample, collected using the CMS detector at the LHC, consists of 5.0 inverse-femtobarns of proton-proton collisions at sqrt(s) = 7 TeV and 19.7 inverse-femtobarns at sqrt(s) = 8 TeV. Top quark pair events containing one electron or muon are selected. The results are presented after correcting for detector effects to allow direct comparison with theoretical predictions. No significant deviations from the predictions of several standard model event simulation generators are observed.
Measurement Of The Differential Cross Sections For Top Quark Pair Production As A Function Of Kinematic Event Variables In Pp Collisions At S
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Author :
language : en
Publisher:
Release Date : 2016
Measurement Of The Differential Cross Sections For Top Quark Pair Production As A Function Of Kinematic Event Variables In Pp Collisions At S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
Measurements are reported of the normalized differential cross sections for top quark pair production with respect to four kinematic event variables: the missing transverse energy; the scalar sum of the jet transverse momentum (pT); the scalar sum of the pT of all objects in the event; and the pT of leptonically decaying W bosons from top quark decays. The data sample, collected using the CMS detector at the LHC, consists of 5.0 fb–1 of proton-proton collisions at √s = 7 TeV and 19.7 fb–1 at √s = 8 TeV. Top quark pair events containing one electron or muon are selected. The results are presented after correcting for detector effects to allow direct comparison with theoretical predictions. In conclusion, no significant deviations from the predictions of several standard model event simulation generators are observed.
Measurement Of The Differential Cross Section For Top Quark Pair Production In Pp Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2015
Measurement Of The Differential Cross Section For Top Quark Pair Production In Pp Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
Observation Of Top Quark Pair Production In Association With A Photon And Measurement Of The Tt U00af Production Cross Section In Pp Collisions At U221a S
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Author :
language : en
Publisher:
Release Date : 2015
Observation Of Top Quark Pair Production In Association With A Photon And Measurement Of The Tt U00af Production Cross Section In Pp Collisions At U221a S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
A search is performed for top-quark pairs (tt¯) produced together with a photon (?) with transverse energy greater than 20 GeV using a sample of tt¯ candidate events in final states with jets, missing transverse momentum, and one isolated electron or muon. The data set used corresponds to an integrated luminosity of 4.59 fb−1 of proton-proton collisions at a center-of-mass energy of 7 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. In total, 140 and 222 tt¯? candidate events are observed in the electron and muon channels, to be compared to the expectation of 79 ± 26 and 120 ± 39 non-tt¯? background events, respectively. The production of tt¯? events is observed with a significance of 5.3 standard deviations away from the null hypothesis. The tt¯? production cross section times the branching ratio (BR) of the single-lepton decay channel is measured in a fiducial kinematic region within the ATLAS acceptance. The measured value is ?fidtt¯? × BR = 63 ± 8(stat)+17–13(syst) ± 1(lumi) fb per lepton flavor, in good agreement with the leading-order theoretical calculation normalized to the next-to-leading-order theoretical prediction of 48 ± 10 fb.
Measurement Of The T Channel Single Top Quark Production Cross Section In Pp Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2011
Measurement Of The T Channel Single Top Quark Production Cross Section In Pp Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
Electroweak production of the top quark is measured in pp collisions at sqrt(s) = 7 TeV, using a dataset collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 36 inverse picobarns. With an event selection optimized for t-channel production, two complementary analyses are performed. The first one exploits the special angular properties of the signal, together with background estimates from data. The second approach uses a multivariate analysis technique to probe the compatibility with signal topology expected from electroweak top quark production. The combined measurement of the cross section is 83.6 +/- 29.8 (stat.+syst.) +/- 3.3 (lumi.) pb, consistent with the standard model expectation.