TOP-12-011
Measurement of the single top t-channel cross section in pp collisions at √s = 8 TeV

Abstract

The measurement of the single top t-channel production cross section in pp collisions at 8 TeV with the CMS detector at the LHC considering the leptonic decay channel with a muon in the final state is presented. After a selection optimized for the t-channel production, the pseudorapidity distribution of the recoil jet is exploitedfor the measurement. The main backgrounds are estimated with data driven techniques. With an integrated luminosity of 5.0 fb−1 the cross section is found to be 80.1 5.7(stat.) 11.0(syst.) 4.0(lumi.) pb in agreement with the standard model prediction.

Public Document

The document CMS-PAS-TOP-12-011 is published on the CERN document server here.

Results

$\sigma ( t-channel, 8TeV) = 80.1 \pm 5.7 (stat.) \pm 11.0 (sys.) \pm 4.0 (lumi)~\%$

$ \sigma ( t-channel, 8TeV) / \sigma ( t-channel, 8TeV) = 1.14 \pm 0.12 (stat) \pm 0.14 (syst) $

$ |V_{tb}|  = 0.96  \pm 0.08 (exp.) \pm 0.02 (th.) $

$  |V_{tb}|  > 0.81~ at ~95 ~\% ~C.L. $ assuming $ 0 < |V_{tb}|  \leq 1 $

Figures

Figure Caption
SR1etaNoVeto10BinsTTFitFixRemodelMuStack.png Result of simultaneous fit to |ηj′| . [pdf]

2J_1Tcosthetalj2_0EtaMuStack.png Distribution of cosθ in the |ηj′| > 2.0 region, obtained normalizing each process yield to the value from the fit. cosθ is defined as the angle between the muon and the non b-tagged jet in the reconstructed top quark rest frame. Due to limited statistic in the simulation, W + Jets background distribution is smoothed through a simple spline. [pdf]

2J_1Tcharge2_0EtaMuStack.png Charge of the muon in muon decay channel normalized to the fit result in the |ηj′| > 2.0 region. [pdf]

2J_1TtopMass2_0EtaMuStack.png Distribution of mlνb in the |ηj′| > 2.0 region, obtained normalizing each process yield to the value from the fit. Due to limited statistic in the simulation, W + Jets background distribution is smoothed through a simple spline. [pdf]

2J_0T_noSyst_etalj_inclusiveMuStack_afterCut.png Distribution of |ηj′| of both jets in the 2-jets 0-tags category. [pdf]

2J_0T_noSyst_topMassMuStack.png Distribution of mlνb in the 2-jets 0-tags category, lowering the pt cut to 40 and releasing the mT cut. [pdf]

3J_1T_noSyst_etalj_afterCutMuStack.png Distribution of |ηj′| in the 3-jets 1-tag category, obtained normalizing each process yield to the value from the fit. Due to limited statistic in the simulation, W+jets background distribution is smoothed through a simple spline. [pdf]

3J_1T_noSyst_topMassMuStack.png Distribution of mlνb in the | in the 3-jets 1-tag category, obtained normalizing each process yield to the value from the fit. Due to limited statistic in the simulation, W+jets background distribution is smoothed through a simple spline. [pdf]

3J_2T_noSyst_etaljMuStack.png Distribution of |ηj′|in the 3-jets 2-tag category, obtained normalizing each process yield to the value from the fit. Due to limited statistic in the simulation, W+jets background distribution is smoothed through a simple spline. [pdf]

3J_2T_noSyst_topMassMuStack.png Distribution of mlνb in the 3-jets 2-tags category, obtained normalizing each process yield to the value from the fit. Due to limited statistic in the simulation, W+jets background distribution is smoothed through a simple spline. [pdf]

finalplot.png Single top cross section in the t channel versus centre-of-mass energy, comparing our measurement with the dedicated t-channel cross section measurements at Tevatron and with the QCD expectations computed with at NLO with MCFM in the 5-flavour scheme and at NLO+NNLL. The error band (width of the curve) is obtained by varying the top mass within its current uncertainty, estimating the PDF uncertainty according to the HEPDATA recommendations, and varying the factorization and renormalization scales coherently by a factor two up and down. [pdf]

Tables

EventsSRSB.png Expected and observed number of events in the 2-jets 1 tag sample, signal and sideband region. Only statistical uncertainties are shown. All numbers refer to MC expectation except for the QCD, which is extracted through a fit to mT. The data/MC excess can be interpreted with an excess of W+Jets which is hinted to by several previous measurements.

SystTable.png Uncertainties on the t-channel cross section.

-- AlbertoOrsoMariaIorio - 14-Sep-2012

Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf 2J_0T_noSyst_etalj_inclusiveMuStack_afterCut.pdf r3 r2 r1 manage 23.1 K 2012-09-18 - 11:00 AlbertoOrsoMariaIorio 2 jets 0 tags inclusive jet eta
PNGpng 2J_0T_noSyst_etalj_inclusiveMuStack_afterCut.png r3 r2 r1 manage 17.0 K 2012-09-18 - 11:00 AlbertoOrsoMariaIorio 2 jets 0 tags inclusive jet eta
PDFpdf 2J_0T_noSyst_topMassMuStack.pdf r2 r1 manage 23.3 K 2012-09-17 - 18:16 AlbertoOrsoMariaIorio 2 jets 0 tags mlbn
PNGpng 2J_0T_noSyst_topMassMuStack.png r2 r1 manage 18.2 K 2012-09-17 - 18:15 AlbertoOrsoMariaIorio 2 jets 0 tags mlbn
PDFpdf 2J_1Tcharge2_0EtaMuStack.pdf r2 r1 manage 16.4 K 2012-09-17 - 18:19 AlbertoOrsoMariaIorio lepton charge plot at |eta_j'|>2.0
PNGpng 2J_1Tcharge2_0EtaMuStack.png r2 r1 manage 12.8 K 2012-09-17 - 18:15 AlbertoOrsoMariaIorio lepton charge plot at |eta_j'|>2.0
PDFpdf 2J_1Tcharge2_5EtaMuStack.pdf r1 manage 16.5 K 2012-09-17 - 18:15 AlbertoOrsoMariaIorio lepton charge plot at |eta_j'|>2.0
PDFpdf 2J_1Tcosthetalj2_0EtaMuStack.pdf r2 r1 manage 19.0 K 2012-09-17 - 18:00 AlbertoOrsoMariaIorio costheta* plot at |eta_j'|>2.0
PNGpng 2J_1Tcosthetalj2_0EtaMuStack.png r2 r1 manage 15.0 K 2012-09-17 - 18:00 AlbertoOrsoMariaIorio costheta* plot at |eta_j'|>2.0
PDFpdf 2J_1TtopMass2_0EtaMuStack.pdf r2 r1 manage 23.6 K 2012-09-17 - 17:56 AlbertoOrsoMariaIorio mlbv plot at |eta_j'|>2.0
PNGpng 2J_1TtopMass2_0EtaMuStack.png r2 r1 manage 17.3 K 2012-09-17 - 17:49 AlbertoOrsoMariaIorio mlbv plot at |eta_j'|>2.0
PDFpdf 2J_1TtopMass2_5EtaMuStack.pdf r1 manage 22.3 K 2012-09-17 - 17:50 AlbertoOrsoMariaIorio mlbv plot at |eta_j'|>2.0
PDFpdf 3J_1T_noSyst_etalj_afterCutMuStack.pdf r2 r1 manage 25.1 K 2012-09-17 - 17:47 AlbertoOrsoMariaIorio 3 jets 1 tag light jet eta normalized to fit results
PNGpng 3J_1T_noSyst_etalj_afterCutMuStack.png r2 r1 manage 17.3 K 2012-09-17 - 17:45 AlbertoOrsoMariaIorio 3 jets 1 tag light jet eta normalized to fit results
PDFpdf 3J_1T_noSyst_topMassMuStack.pdf r2 r1 manage 23.7 K 2012-09-17 - 17:38 AlbertoOrsoMariaIorio 3 jets 1 tag mlbv normalized to fit results
PNGpng 3J_1T_noSyst_topMassMuStack.png r2 r1 manage 16.5 K 2012-09-17 - 17:37 AlbertoOrsoMariaIorio 3 jets 1 tag mlbv normalized to fit results
PDFpdf 3J_2T_noSyst_etaljMuStack.pdf r2 r1 manage 22.1 K 2012-09-17 - 17:19 AlbertoOrsoMariaIorio 3 jets 2 tags light jet eta normalized to fit results
PNGpng 3J_2T_noSyst_etaljMuStack.png r2 r1 manage 15.0 K 2012-09-17 - 17:19 AlbertoOrsoMariaIorio 3 jets 2 tags light jet eta normalized to fit results
PDFpdf 3J_2T_noSyst_topMassMuStack.pdf r2 r1 manage 22.2 K 2012-09-17 - 17:18 AlbertoOrsoMariaIorio 3 jets 2 tags mlbv normalized to fit results
PNGpng 3J_2T_noSyst_topMassMuStack.png r2 r1 manage 15.5 K 2012-09-17 - 17:18 AlbertoOrsoMariaIorio 3 jets 2 tags mlbv normalized to fit results
PNGpng CrossSec.png r1 manage 10.8 K 2012-09-15 - 17:35 AlbertoOrsoMariaIorio Cross section
PNGpng EventsSRSB.png r1 manage 77.4 K 2012-09-15 - 16:42 AlbertoOrsoMariaIorio Table of number of events in signal/sideband region
PNGpng Ratio.png r1 manage 12.8 K 2012-09-15 - 17:34 AlbertoOrsoMariaIorio Cross section ratio 8TeV/7TeV
PDFpdf SR1etaNoVeto10BinsTTFitFixRemodelMuStack.pdf r2 r1 manage 17.3 K 2012-09-17 - 17:15 AlbertoOrsoMariaIorio eta j' fit result
PNGpng SR1etaNoVeto10BinsTTFitFixRemodelMuStack.png r2 r1 manage 12.3 K 2012-09-17 - 17:14 AlbertoOrsoMariaIorio eta j' fit result
PNGpng SystTable.png r1 manage 94.3 K 2012-09-15 - 16:47 AlbertoOrsoMariaIorio Uncertainties on the t-channel cross section
PNGpng Vtb.png r1 manage 13.9 K 2012-09-15 - 17:33 AlbertoOrsoMariaIorio |Vtb|
PNGpng Vtb_constr.png r2 r1 manage 5.2 K 2012-09-15 - 17:36 AlbertoOrsoMariaIorio |Vtb| assuming |Vtb|<1
PDFpdf finalplot.pdf r1 manage 14.9 K 2012-09-15 - 05:12 AlbertoOrsoMariaIorio Cross section as a function of the center of mass energy
PNGpng finalplot.png r1 manage 16.7 K 2012-09-15 - 05:14 AlbertoOrsoMariaIorio Cross section as a function of the center of mass energy
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Topic revision: r7 - 2013-03-06 - AlbertoOrsoMariaIorio
 
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