TOP-11-013
Measurements of the differential top quark pair production cross sections

Abstract

Normalized differential ttbar quark pair production cross sections in pp-collisions at sqrt{s} = 7 TeV are measured using a dataset recorded by the CMS experiment in 2011 corresponding to an integrated luminosity of 1.14 fb-1. The measurement is performed in the semileptonic decay channels (muon+jets and electron+jets) and the decay channels into two opposite-sign leptons (m+m-, e+e- and m+/- e-/+) in the final state. The cross section distributions are measured as a function of kinematic observables of the final state leptons and the top quarks, as reconstructed by algorithms fitting the ttbar event topologies. The measurement also includes the invariant mass distribution of ttbar quark pairs. The measurement shows good agreement with predictions from QCD models.

Public Document

The document CMS-PAS-TOP-11-013 published on the CERN document server can be found here.

Figures

Basic kinematic distributions after event selection in the lepton+jets channel

Figure Caption
mujets_nbottomJetKinematics.png Basic kinematic distributions after event selection for mu+jets channel: number of b-tagged jets before requiring any selection on this variable, illustrating that the main background from W+jets is efficiently suppressed by requiring b-tagging. The simulated events are corrected for trigger and lepton selection efficiencies. The hatched area represents the uncertainty coming from the inclusive ttbar cross section measurement and the luminosity. [Get pdf version]
mujets_ntightJetKinematicsTagged.png Basic kinematic distributions after event selection for mu+jets: jet multiplicity after requiring b-tagging demonstrating that mainly ttbar events are selected. The simulated events are corrected for trigger and lepton selection efficiencies. After imposing the b-tag requirement, the events are scaled with a b-tagging efficiency in addition. The hatched area represents the uncertainty coming from the inclusive ttbar cross section measurement and the luminosity. [Get pdf version]
ejets_nbottomJetKinematics.png Basic kinematic distributions after event selection for e+jets channel: number of b-tagged jets before requiring any selection on this variable, illustrating that the main background from W+jets is efficiently suppressed by requiring b-tagging. The simulated events are corrected for trigger and lepton selection efficiencies. The hatched area represents the uncertainty coming from the inclusive ttbar cross section measurement and the luminosity. [Get pdf version]
ejets_ntightJetKinematicsTagged.png Basic kinematic distributions after event selection for e+jets: jet multiplicity after requiring b-tagging demonstrating that mainly ttbar events are selected. The simulated events are corrected for trigger and lepton selection efficiencies. After imposing the b-tag requirement, the events are scaled with a b-tagging efficiency in addition. The hatched area represents the uncertainty coming from the inclusive ttbar cross section measurement and the luminosity. [Get pdf version]

Basic kinematic distributions after event selection in the dilepton channel

Figure Caption
dileptons_combinedLeptonsPt.png Basic kinematic distributions after event selection for the dilepton channels: transverse momentum pT of the selected isolated leptons. The Drell--Yan background is rescaled to the data-driven estimated factor given in the legends. The hatched area represents the uncertainty coming from the inclusive ttbar cross section measurement and the luminosity. [Get pdf version]
dileptons_combinedJetsPt.png Basic kinematic distributions after event selection for the dilepton channels: transverse momentum pT of the reconstructed jets. The Drell--Yan background is rescaled to the data-driven estimated factor given in the legends. The hatched area represents the uncertainty coming from the inclusive ttbar cross section measurement and the luminosity. [Get pdf version]
dileptons_combinedJetsMulti.png Basic kinematic distributions after event selection for the dilepton channels: multiplicity of the reconstructed jets after b-tagging. The Drell--Yan background is rescaled to the data-driven estimated factor given in the legends. The hatched area represents the uncertainty coming from the inclusive ttbar cross section measurement and the luminosity. [Get pdf version]
dileptons_combinedJetsMultiTCHEL.png Basic kinematic distributions after event selection for the dilepton channels: multiplicity of b-tagged jets. The Drell--Yan background is rescaled to the data-driven estimated factor given in the legends. The hatched area represents the uncertainty coming from the inclusive ttbar cross section measurement and the luminosity. [Get pdf version]

Normalized differential cross sections in the lepton+jets channel

Figure Caption
finalXSeclepPtNormCombined_log.png Combined normalized differential cross sections in the lepton+jets channel: lepton pT. The inner error bars indicate the statistical uncertainty and the outer error bars the combined statistical and systematic uncertainty. The measurements are compared to predictions from MadGraph, POWHEG, and MC@NLO Monte Carlo generators. For the MadGraph comparison both a smooth curve and a binned histogram are shown. The latter indicates the bins of the cross section measurement. [Get pdf version] [Get pdf version in linear scale]
finalXSeclepEtaNormCombined_linear.png Combined normalized differential cross sections in the lepton+jets channel: lepton pseudo-rapidity. The inner error bars indicate the statistical uncertainty and the outer error bars the combined statistical and systematic uncertainty. The measurements are compared to predictions from MadGraph, POWHEG, and MC@NLO Monte Carlo generators. For the MadGraph comparison both a smooth curve and a binned histogram are shown. The latter indicates the bins of the cross section measurement. [Get pdf version]
finalXSectopPtNormCombined_log.png Combined normalized differential cross sections in the lepton+jets channel: top/antitop pT. The inner error bars indicate the statistical uncertainty and the outer error bars the combined statistical and systematic uncertainty. The measurements are compared to predictions from MadGraph, POWHEG, and MC@NLO Monte Carlo generators. For the MadGraph comparison both a smooth curve and a binned histogram are shown. The latter indicates the bins of the cross section measurement. [Get pdf version] [Get pdf version in linear scale]
finalXSectopYNormCombined_linear.png Combined normalized differential cross sections in the lepton+jets channel: top/antitop rapidity. The inner error bars indicate the statistical uncertainty and the outer error bars the combined statistical and systematic uncertainty. The measurements are compared to predictions from MadGraph, POWHEG, and MC@NLO Monte Carlo generators. For the MadGraph comparison both a smooth curve and a binned histogram are shown. The latter indicates the bins of the cross section measurement. [Get pdf version]
finalXSecttbarPtNormCombined_log.png Combined normalized differential cross sections in the lepton+jets channel: pT of the ttbar system. The inner error bars indicate the statistical uncertainty and the outer error bars the combined statistical and systematic uncertainty. The measurements are compared to predictions from MadGraph, POWHEG, and MC@NLO Monte Carlo generators. For the MadGraph comparison both a smooth curve and a binned histogram are shown. The latter indicates the bins of the cross section measurement. [Get pdf version] [Get pdf version in linear scale]
finalXSecttbarYNormCombined_linear.png Combined normalized differential cross sections in the lepton+jets channel: rapidity of the ttbar system. The inner error bars indicate the statistical uncertainty and the outer error bars the combined statistical and systematic uncertainty. The measurements are compared to predictions from MadGraph, POWHEG, and MC@NLO Monte Carlo generators. For the MadGraph comparison both a smooth curve and a binned histogram are shown. The latter indicates the bins of the cross section measurement. [Get pdf version]
finalXSecttbarMassNormCombined_log.png Combined normalized differential cross sections in the lepton+jets channel: invariant mass of the ttbar system. The inner error bars indicate the statistical uncertainty and the outer error bars the combined statistical and systematic uncertainty. The measurements are compared to predictions from MadGraph, POWHEG, and MC@NLO Monte Carlo generators. For the MadGraph comparison both a smooth curve and a binned histogram are shown. The latter indicates the bins of the cross section measurement. [Get pdf version]

Normalized differential cross sections in the dilepton channel

Figure Caption
combined_Cross_Leptons_Pt_log.png Combined normalized differential cross sections in the dilepton channel: leptons pT. The inner error bars indicate the statistical uncertainty and the outer error bars the combined statistical and systematic uncertainty. The measurements are compared to predictions from MadGraph, POWHEG, and MC@NLO Monte Carlo generators. For the MadGraph comparison both a smooth curve and a binned histogram are shown. The latter indicates the bins of the cross section measurement. [Get pdf version] [Get pdf version in linear scale]
combined_Cross_Leptons_Eta.png Combined normalized differential cross sections in the dilepton channel: leptons pseudo-rapidity. The inner error bars indicate the statistical uncertainty and the outer error bars the combined statistical and systematic uncertainty. The measurements are compared to predictions from MadGraph, POWHEG, and MC@NLO Monte Carlo generators. For the MadGraph comparison both a smooth curve and a binned histogram are shown. The latter indicates the bins of the cross section measurement. [Get pdf version]
combined_Cross_LepPair_Pt_log.png Combined normalized differential cross sections in the dilepton channel: pT of the lepton pair. The inner error bars indicate the statistical uncertainty and the outer error bars the combined statistical and systematic uncertainty. The measurements are compared to predictions from MadGraph, POWHEG, and MC@NLO Monte Carlo generators. For the MadGraph comparison both a smooth curve and a binned histogram are shown. The latter indicates the bins of the cross section measurement. [Get pdf version] [Get pdf version in linear scale]
combined_Cross_LepPair_Mass.png Combined normalized differential cross sections in the dilepton channel: invariant mass of the lepton pair. The inner error bars indicate the statistical uncertainty and the outer error bars the combined statistical and systematic uncertainty. The measurements are compared to predictions from MadGraph, POWHEG, and MC@NLO Monte Carlo generators. For the MadGraph comparison both a smooth curve and a binned histogram are shown. The latter indicates the bins of the cross section measurement. [Get pdf version]
combined_Cross_TopQuarks_Pt_log.png Combined normalized differential cross sections in the dilepton channel: top/antitop pT. The inner error bars indicate the statistical uncertainty and the outer error bars the combined statistical and systematic uncertainty. The measurements are compared to predictions from MadGraph, POWHEG, and MC@NLO Monte Carlo generators. For the MadGraph comparison both a smooth curve and a binned histogram are shown. The latter indicates the bins of the cross section measurement. [Get pdf version] [Get pdf version in linear scale]
combined_Cross_TopQuarks_Rapidity.png Combined normalized differential cross sections in the dilepton channel: top/antitop rapidity. The inner error bars indicate the statistical uncertainty and the outer error bars the combined statistical and systematic uncertainty. The measurements are compared to predictions from MadGraph, POWHEG, and MC@NLO Monte Carlo generators. For the MadGraph comparison both a smooth curve and a binned histogram are shown. The latter indicates the bins of the cross section measurement. [Get pdf version]
combined_Cross_TtBar_Pt_log.png Combined normalized differential cross sections in the dilepton channel: pT of the ttbar system. The inner error bars indicate the statistical uncertainty and the outer error bars the combined statistical and systematic uncertainty. The measurements are compared to predictions from MadGraph, POWHEG, and MC@NLO Monte Carlo generators. For the MadGraph comparison both a smooth curve and a binned histogram are shown. The latter indicates the bins of the cross section measurement. [Get pdf version] [Get pdf version in linear scale]
combined_Cross_TtBar_Rapidity.png Combined normalized differential cross sections in the dilepton channel: rapidity of the ttbar system. The inner error bars indicate the statistical uncertainty and the outer error bars the combined statistical and systematic uncertainty. The measurements are compared to predictions from MadGraph, POWHEG, and MC@NLO Monte Carlo generators. For the MadGraph comparison both a smooth curve and a binned histogram are shown. The latter indicates the bins of the cross section measurement. [Get pdf version]
c_unfold_Normalized_dSigmadM.png Combined normalized differential cross sections in the dilepton channel: invariant mass of the ttbar system. The inner error bars indicate the statistical uncertainty and the outer error bars the combined statistical and systematic uncertainty. The measurements are compared to predictions from MadGraph, POWHEG, and MC@NLO Monte Carlo generators. For the MadGraph comparison both a smooth curve and a binned histogram are shown. The latter indicates the bins of the cross section measurement. [Get pdf version]
Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf c_unfold_Normalized_dSigmadM.pdf r1 manage 26.0 K 2012-02-07 - 19:15 MariaAldaya  
PNGpng c_unfold_Normalized_dSigmadM.png r1 manage 23.1 K 2012-02-07 - 19:15 MariaAldaya  
PDFpdf combined_Cross_LepPair_Mass.pdf r1 manage 7.7 K 2012-02-07 - 19:10 MariaAldaya  
PNGpng combined_Cross_LepPair_Mass.png r1 manage 24.0 K 2012-02-07 - 19:09 MariaAldaya  
PDFpdf combined_Cross_LepPair_Pt_lin.pdf r1 manage 7.8 K 2012-02-07 - 19:08 MariaAldaya  
PDFpdf combined_Cross_LepPair_Pt_log.pdf r1 manage 7.2 K 2012-02-07 - 19:08 MariaAldaya  
PNGpng combined_Cross_LepPair_Pt_log.png r1 manage 24.2 K 2012-02-07 - 19:07 MariaAldaya  
PDFpdf combined_Cross_Leptons_Eta.pdf r1 manage 7.4 K 2012-02-07 - 19:07 MariaAldaya  
PNGpng combined_Cross_Leptons_Eta.png r1 manage 23.5 K 2012-02-07 - 19:07 MariaAldaya  
PDFpdf combined_Cross_Leptons_Pt_lin.pdf r1 manage 6.8 K 2012-02-07 - 19:06 MariaAldaya  
PDFpdf combined_Cross_Leptons_Pt_log.pdf r1 manage 6.7 K 2012-02-07 - 19:06 MariaAldaya  
PNGpng combined_Cross_Leptons_Pt_log.png r1 manage 22.4 K 2012-02-07 - 19:05 MariaAldaya  
PDFpdf combined_Cross_TopQuarks_Pt_lin.pdf r1 manage 7.9 K 2012-02-07 - 19:14 MariaAldaya  
PDFpdf combined_Cross_TopQuarks_Pt_log.pdf r1 manage 7.2 K 2012-02-07 - 19:13 MariaAldaya  
PNGpng combined_Cross_TopQuarks_Pt_log.png r1 manage 24.9 K 2012-02-07 - 19:13 MariaAldaya  
PDFpdf combined_Cross_TopQuarks_Rapidity.pdf r1 manage 7.7 K 2012-02-07 - 19:14 MariaAldaya  
PNGpng combined_Cross_TopQuarks_Rapidity.png r1 manage 24.3 K 2012-02-07 - 19:14 MariaAldaya  
PDFpdf combined_Cross_TtBar_Pt_lin.pdf r1 manage 7.4 K 2012-02-07 - 19:18 MariaAldaya  
PDFpdf combined_Cross_TtBar_Pt_log.pdf r1 manage 6.4 K 2012-02-07 - 19:17 MariaAldaya  
PNGpng combined_Cross_TtBar_Pt_log.png r1 manage 20.5 K 2012-02-07 - 19:17 MariaAldaya  
PDFpdf combined_Cross_TtBar_Rapidity.pdf r1 manage 7.6 K 2012-02-07 - 19:19 MariaAldaya  
PNGpng combined_Cross_TtBar_Rapidity.png r1 manage 23.7 K 2012-02-07 - 19:18 MariaAldaya  
PDFpdf dileptons_combinedJetsMulti.pdf r1 manage 6.9 K 2012-02-07 - 17:43 MariaAldaya  
PNGpng dileptons_combinedJetsMulti.png r1 manage 14.9 K 2012-02-07 - 17:42 MariaAldaya  
PDFpdf dileptons_combinedJetsMultiTCHEL.pdf r1 manage 6.8 K 2012-02-07 - 17:41 MariaAldaya  
PNGpng dileptons_combinedJetsMultiTCHEL.png r1 manage 15.0 K 2012-02-07 - 17:41 MariaAldaya  
PDFpdf dileptons_combinedJetsPt.pdf r1 manage 11.5 K 2012-02-07 - 17:40 MariaAldaya  
PNGpng dileptons_combinedJetsPt.png r1 manage 21.2 K 2012-02-07 - 17:40 MariaAldaya  
PDFpdf dileptons_combinedLeptonsPt.pdf r1 manage 10.0 K 2012-02-07 - 17:40 MariaAldaya  
PNGpng dileptons_combinedLeptonsPt.png r1 manage 20.4 K 2012-02-07 - 17:39 MariaAldaya  
PDFpdf ejets_nbottomJetKinematics.pdf r1 manage 6.0 K 2012-02-07 - 17:37 MariaAldaya  
PNGpng ejets_nbottomJetKinematics.png r1 manage 15.5 K 2012-02-07 - 17:37 MariaAldaya  
PDFpdf ejets_ntightJetKinematicsTagged.pdf r1 manage 6.1 K 2012-02-07 - 17:38 MariaAldaya  
PNGpng ejets_ntightJetKinematicsTagged.png r1 manage 14.7 K 2012-02-07 - 17:38 MariaAldaya  
PDFpdf finalXSeclepEtaNormCombined_linear.pdf r1 manage 7.4 K 2012-02-07 - 18:28 MariaAldaya  
PNGpng finalXSeclepEtaNormCombined_linear.png r1 manage 25.1 K 2012-02-07 - 18:27 MariaAldaya  
PDFpdf finalXSeclepPtNormCombined_linear.pdf r1 manage 10.2 K 2012-02-07 - 18:27 MariaAldaya  
PDFpdf finalXSeclepPtNormCombined_log.pdf r1 manage 9.7 K 2012-02-07 - 18:26 MariaAldaya  
PNGpng finalXSeclepPtNormCombined_log.png r1 manage 21.1 K 2012-02-07 - 18:25 MariaAldaya  
PDFpdf finalXSectopPtNormCombined_linear.pdf r1 manage 7.2 K 2012-02-07 - 18:30 MariaAldaya  
PDFpdf finalXSectopPtNormCombined_log.pdf r1 manage 6.7 K 2012-02-07 - 18:30 MariaAldaya  
PNGpng finalXSectopPtNormCombined_log.png r1 manage 21.6 K 2012-02-07 - 18:30 MariaAldaya  
PDFpdf finalXSectopYNormCombined_linear.pdf r1 manage 13.6 K 2012-02-07 - 18:32 MariaAldaya  
PNGpng finalXSectopYNormCombined_linear.png r1 manage 25.7 K 2012-02-07 - 18:31 MariaAldaya  
PDFpdf finalXSecttbarMassNormCombined_log.pdf r1 manage 25.0 K 2012-02-07 - 18:42 MariaAldaya  
PNGpng finalXSecttbarMassNormCombined_log.png r1 manage 22.5 K 2012-02-07 - 18:41 MariaAldaya  
PDFpdf finalXSecttbarPtNormCombined_linear.pdf r1 manage 11.4 K 2012-02-07 - 18:40 MariaAldaya  
PDFpdf finalXSecttbarPtNormCombined_log.pdf r1 manage 12.0 K 2012-02-07 - 18:40 MariaAldaya  
PNGpng finalXSecttbarPtNormCombined_log.png r1 manage 21.8 K 2012-02-07 - 18:39 MariaAldaya  
PDFpdf finalXSecttbarYNormCombined_linear.pdf r1 manage 7.9 K 2012-02-07 - 18:41 MariaAldaya  
PNGpng finalXSecttbarYNormCombined_linear.png r1 manage 22.3 K 2012-02-07 - 18:41 MariaAldaya  
PDFpdf mujets_nbottomJetKinematics.pdf r1 manage 6.4 K 2012-02-07 - 16:52 MariaAldaya  
PNGpng mujets_nbottomJetKinematics.png r1 manage 15.6 K 2012-02-07 - 16:51 MariaAldaya  
PDFpdf mujets_ntightJetKinematicsTagged.pdf r1 manage 6.3 K 2012-02-07 - 16:53 MariaAldaya  
PNGpng mujets_ntightJetKinematicsTagged.png r1 manage 14.9 K 2012-02-07 - 16:52 MariaAldaya  
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