TOP-12-007: Measurement of the ttbar production cross section in the dilepton channel in pp collisions at sqrt(s) = 8 TeV

Abstract

The cross section for top quark-antiquark pair production is measured in proton-proton collisions at sqrt(s) = 8 TeV in a data sample corresponding to 2.41 fb-1 of integrated luminosity collected by the CMS experiment in 2012. The measurement is performed with events with two energetic leptons (electrons or muons) in the final state. Presence of the b-quark jets in the top-quark decays is required. The method used to extract the cross section is a simple and robust counting experiment. The measured cross section is found to be 227 3 (stat.) 10 (syst.) 10 (lumi.) pb, in agreement with theoretical predictions.

Approved Plots and Tables from TOP-12-007

Supporting Tables

Table Caption

Break_down_per_channel_2410pb-1_JEC2012.png Summary of the relative systematic uncertainties in percentage on the number of signal top antitop events after the full selection criteria, shown separately for each of the dilepton channels.
Cross_section_2410pb-1_JEC2012.png Expected signal and background contributions compared to the number of events observed in data passing full signal selection with at least one b-tagged jet required, and the resulting cross section measurements. Drell-Yan ee, mu mu backgrounds from data-based methods. The errors quoted for signal and backgrounds correspond to statistical and systematic uncertainties. The uncertainties on the cross section include statistical, systematic, and luminosity normalisation uncertainties.
Break_down_combination_2410pb-1_JEC2012.png Break-down of the statistical and systematic uncertainties contributing to the combined cross section measurement given inclusively and in percentage.

Supporting Figures

Figure Caption
hPtLepton0_EE_2jets.gif Distributions in pt for electrons after the selection on jet multiplicity, and the corresponding data to simulation ratios.The expected distributions for ttbar signal and background sources are shown by histograms. A ttbar cross section of 225.2 pb is used to normalize the simulated ttbar signal.The systematic uncertainties are displayed by the hatched regions. Click on figures to get their pdf version.
hPtLepton0_MM_2jets.gif Distributions in pt for muons after the selection on jet multiplicity, and the corresponding data to simulation ratios.The expected distributions for ttbar signal and background sources are shown by histograms. A ttbar cross section of 225.2 pb is used to normalize the simulated ttbar signal.The systematic uncertainties are displayed by the hatched regions. Click on figures to get their pdf version.
hPtJet0_ALL_2jets.gif Distributions in pt for jets of highest pt after the selection on jet multiplicity, and the corresponding data to simulation ratios.The expected distributions for ttbar signal and background sources are shown by histograms. A ttbar cross section of 225.2 pb is used to normalize the simulated ttbar signal.The systematic uncertainties are displayed by the hatched regions. Click on figures to get their pdf version.
hInvMass_EM_2jets.gif Dilepton invariant mass distribution after the selection on jet multiplicity for the emu channel, and the corresponding data to simulation ratios. The expected distributions for ttbar signal and background sources are shown by histograms. A ttbar cross section of 225.2 pb is used to normalize the simulated ttbar signal. Click on figures to get their pdf version.
hInvMass_MMEE_2jets.gif Dilepton invariant mass distribution after the selection on jet multiplicity for the summed ee and mumu channels, and the corresponding data to simulation ratios. The expected distributions for ttbar signal and background sources are shown by histograms. A ttbar cross section of 225.2 pb is used to normalize the simulated ttbar signal. Click on figures to get their pdf version.
hMET_EM_2jets.gif Missing ET distributions after the selection on jet multiplicity, for the emu channel. Click on figures to get their pdf version.
hMET_MMEE_2jets.gif Missing ET distributions after the selection on jet multiplicity, for the summed ee and mumu channels. Click on figures to get their pdf version.
hNJets_EM_MET_NoJetCut.gif The jet multiplicity for events passing the dilepton selection and the missing ET criteria, for the emu channel. Click on figures to get their pdf version.
hNJets_MMEE_MET_NoJetCut.gif The jet multiplicity for events passing the dilepton selection and the missing ET criteria, for the sum of ee and mumu channels. Click on figures to get their pdf version.
hNJetsBtag_EM_MET.gif The multiplicity of b-tagged jets in events passing the full event selections (but without cutting in number of b-tagged jets), for the emu channel. Click on figures to get their pdf version.
hNJetsBtag_MMEE_MET.gif The multiplicity of b-tagged jets in events passing the full event selections (but without cutting in number of b-tagged jets), for the summed ee and mumu channels. Click on figures to get their pdf version.

-- LucaScodellaro - 1-Jul-2012

Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf Break_down_combination_2410pb-1_JEC2012.pdf r1 manage 14.2 K 2012-07-01 - 13:39 JavierCuevas  
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PDFpdf Break_down_per_channel_2410pb-1_JEC2012.pdf r1 manage 11.9 K 2012-07-01 - 12:44 JavierCuevas  
PNGpng Break_down_per_channel_2410pb-1_JEC2012.png r1 manage 27.0 K 2012-07-01 - 12:52 JavierCuevas  
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PDFpdf DYestimate_2410_JEC2012.pdf r1 manage 13.6 K 2012-07-01 - 12:27 JavierCuevas  
PNGpng DYestimate_2410_JEC2012.png r1 manage 44.1 K 2012-07-01 - 12:30 JavierCuevas  
GIFgif hInvMass_EM_2jets.gif r1 manage 26.4 K 2012-06-30 - 18:31 Sluca  
PDFpdf hInvMass_EM_2jets.pdf r1 manage 25.9 K 2012-06-30 - 18:31 Sluca  
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GIFgif hMET_MMEE_2jets.gif r1 manage 25.1 K 2012-06-30 - 18:48 Sluca  
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GIFgif hNJetsBtag_EM_MET.gif r2 r1 manage 21.6 K 2012-07-03 - 15:13 Sluca  
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PDFpdf hNJets_EM_MET_NoJetCut.pdf r1 manage 16.2 K 2012-06-30 - 18:48 Sluca  
GIFgif hNJets_MMEE_MET_NoJetCut.gif r1 manage 21.0 K 2012-06-30 - 18:48 Sluca  
PDFpdf hNJets_MMEE_MET_NoJetCut.pdf r1 manage 16.2 K 2012-06-30 - 18:48 Sluca  
GIFgif hPtJet0_ALL_2jets.gif r1 manage 26.0 K 2012-06-30 - 18:02 Sluca  
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GIFgif hPtLepton0_EE_2jets.gif r1 manage 25.4 K 2012-06-30 - 17:47 Sluca  
PDFpdf hPtLepton0_EE_2jets.pdf r1 manage 22.1 K 2012-06-30 - 18:02 Sluca  
GIFgif hPtLepton0_MM_2jets.gif r1 manage 25.1 K 2012-06-30 - 18:02 Sluca  
PDFpdf hPtLepton0_MM_2jets.pdf r1 manage 22.1 K 2012-06-30 - 18:02 Sluca  
GIFgif top-EE_Nominal-tex.gif r2 r1 manage 6.2 K 2012-06-30 - 23:16 Sluca  
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PNGpng top-EE_Nominal-tex.png r1 manage 8.4 K 2012-06-30 - 23:17 Sluca  
PDFpdf top-EM_Nominal-tex.pdf r1 manage 14.5 K 2012-07-01 - 12:12 JavierCuevas  
PNGpng top-EM_Nominal-tex.png r1 manage 48.6 K 2012-07-01 - 12:15 JavierCuevas  
GIFgif top-MM_Nominal-tex.gif r1 manage 8.3 K 2012-07-01 - 11:54 JavierCuevas  
PDFpdf top-MM_Nominal-tex.pdf r1 manage 14.5 K 2012-07-01 - 11:57 JavierCuevas  
PNGpng top-MM_Nominal-tex.png r1 manage 47.8 K 2012-07-01 - 12:05 JavierCuevas  
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