TOP-11-015
Measurement of the top quark mass in the muon+jets channel

Abstract

We present a measurement of the top quark mass using a sample of ttbar candidate events with one muon and at least four jets in the final state, collected by CMS in pp collisions at √s=7 TeV. From the full 2011 dataset, corresponding to an integrated luminosity of 4.7/fb, 2391 candidate events are selected. Using a likelihood method, the top quark mass is measured from the kinematic configuration simultaneously with the jet energy scale (JES) to be mt = 172.6 0.6 (stat+JES) 1.2 (syst) GeV.

Public Document

The document CMS-PAS-TOP-11-015 published on the CERN document server can be found here.

Result

resulttext.png

(The systematic uncertainty excludes the uncertainty due to non-perturbative QCD effects.)

Figures

Basic kinematic distributions after event selection

Figure Caption
leptonPt_event.png Distribution of muon transverse momentum after the event selection. The simulated samples are rescaled to a luminosity of 4.7/fb. For the ttbar normalization a previous CMS cross-section measurement (CMS-PAS-TOP-11-001) is used, its uncertainty is indicated by the shaded area. [Get pdf version]
leptonEta_event.png Distribution of muon pseudorapidity after the event selection. The simulated samples are rescaled to a luminosity of 4.7/fb. For the ttbar normalization a previous CMS cross-section measurement (CMS-PAS-TOP-11-001) is used, its uncertainty is indicated by the shaded area. [Get pdf version]

W boson and top quark mass before and after the kinematic fit and final selection step

Figure Caption
hadTopRawMass.png The reconstructed top quark mass for the hadronically decaying top quark before the cut on the kinematic fit probability. The simulated samples are rescaled to a luminosity of 4.7/fb. For the ttbar normalization a previous CMS cross-section measurement (CMS-PAS-TOP-11-001) is used, its uncertainty is indicated by the shaded area. [Get pdf version]
hadTopMass_weighted.png The top quark mass from the kinematic fit after the fit probability cut and the weighting by P_fit. The simulated samples are rescaled to a luminosity of 4.7/fb. For the ttbar normalization a previous CMS cross-section measurement (CMS-PAS-TOP-11-001) is used, its uncertainty is indicated by the shaded area. [Get pdf version]
hadWRawMass.png The reconstructed W boson mass for the hadronically decaying top quark before the cut on the kinematic fit probability. The simulated samples are rescaled to a luminosity of 4.7/fb. For the ttbar normalization a previous CMS cross-section measurement (CMS-PAS-TOP-11-001) is used, its uncertainty is indicated by the shaded area. [Get pdf version]
hadWRawMass_weighted.png The reconstructed W boson mass for the hadronically decaying top quark after the fit probability cut and the weighting by P_fit. The simulated samples are rescaled to a luminosity of 4.7/fb. For the ttbar normalization a previous CMS cross-section measurement (CMS-PAS-TOP-11-001) is used, its uncertainty is indicated by the shaded area. [Get pdf version]
hitFitProb.png Distribution of the fit probability of the kinematic fit. A cut is imposed to enhance the fraction f_cp of correct permutations. P_fit is then used as a weight for each permutation in the subsequent steps. The vertical dashed line indicates the cut value of 0.2. The simulated samples are rescaled to a luminosity of 4.7/fb. For the ttbar normalization a previous CMS cross-section measurement (CMS-PAS-TOP-11-001) is used, its uncertainty is indicated by the shaded area. [Get pdf version]

Probality density functions and fit calibration

Figure Caption
mt_mass_cp.png Distributions of the top quark mass from the kinematic fit of correct permutations for different generated top masses with JES=1, fitted with Breit-Wigner peaks convoluted with Gaussian resolution. The vertical dashed line indicates a top quark mass value of 172.5 GeV. [Get pdf version]
mt_mass_wp.png Distributions of the top quark mass from the kinematic fit of wrong permutations for different generated top masses with JES=1, fitted with Crystal Ball distributions. The vertical dashed line indicates a top quark mass value of 172.5 GeV. [Get pdf version]
mt_mass_un.png Distributions of the top quark mass from the kinematic fit of unmatched permutations for different generated top masses with JES=1, fitted with Crystal Ball distributions. The vertical dashed line indicates a top quark mass value of 172.5 GeV. [Get pdf version]
mt_jes_cp.png Distributions of the top quark mass from the kinematic fit of correct permutations for different jet energy scales with m_t,gen = 172.5 GeV, fitted with Breit-Wigner peaks convoluted with Gaussian resolution. The vertical dashed line indicates a top quark mass value of 172.5 GeV. [Get pdf version]
mt_jes_wp.png Distributions of the top quark mass from the kinematic fit of wrong permutations for different jet energy scales with m_t,gen = 172.5 GeV, fitted with Crystal Ball distributions. The vertical dashed line indicates a top quark mass value of 172.5 GeV. [Get pdf version]
mt_jes_un.png Distributions of the top quark mass from the kinematic fit of unmatched permutations for different jet energy scales with m_t,gen = 172.5 GeV, fitted with Crystal Ball distributions. The vertical dashed line indicates a top quark mass value of 172.5 GeV. [Get pdf version]
mW_jes_cp.png Distributions of the reconstructed W boson mass of correct permutations for different jet energy scales with m_t,gen = 172.5 GeV, fitted with asymmetric Gaussian distributions. The vertical dashed line indicates a W boson mass value of 80.4 GeV. [Get pdf version]
mW_jes_wp.png Distributions of the reconstructed W boson mass of wrong permutations for different jet energy scales with m_t,gen = 172.5 GeV, fitted with asymmetric Gaussian distributions. The vertical dashed line indicates a W boson mass value of 80.4 GeV. [Get pdf version]
mW_jes_un.png Distributions of the reconstructed W boson mass of unmatched permutations for different jet energy scales with m_t,gen = 172.5 GeV, fitted with asymmetric Gaussian distributions. The vertical dashed line indicates a W boson mass value of 80.4 GeV. [Get pdf version]
fit_Mass.png Difference between the measured and the generated top mass before calibration for different generated top masses and three different JES. The ideogram method is able to measure the mass input values with a small bias even before calibration. [Get pdf version]
fit_JES.png Difference the measured and the generated JES before calibration for different generated top masses and three different JES. The ideogram method is able to measure the JES input values with a small bias even before calibration. [Get pdf version]
fit_MassPull.png Width of the pull distribution for the measured top mass before calibration for different generated top masses and three different JES. [Get pdf version]
fit_JESPull.png Width of the pull distribution for the measured JES before calibration for different generated top masses and three different JES. [Get pdf version]

Result

Figure Caption
Run2011_0_0.png The 2D likelihood measured on 4.7/fb 2011 data. The contours correspond to 1, 2 and 3 sigma uncertainty. [Get pdf version]
cError_250.png The uncertainty distribution obtained from 8000 pseudo-experiments is compared to the measured uncertainty in data. [Get pdf version]

Cross-check

Figure Caption
doubles_hitFitTtSemiLepEvent_MT_TOP_0Muo.png Distribution of the reconstructed top mass after the kinematic fit, for the permutation with the lowest chi^2, in the cross-check analysis. [Get pdf version]. The cross check result is mt = 172.6 0.2 (stat) 1.8 (syst) GeV with a fixed JES=1.0.

Table of systematic uncertainties

sys. table

(The systematic uncertainty excludes the uncertainty due to non-perturbative QCD effects.)

-- HartmutStadie - 29-Feb-2012

Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf Run2011_0_0.pdf r2 r1 manage 26.1 K 2012-02-28 - 11:56 HartmutStadie  
PNGpng Run2011_0_0.png r4 r3 r2 r1 manage 183.3 K 2012-02-28 - 12:23 HartmutStadie  
PNGpng Run2011_0_0_250.png r2 r1 manage 38.7 K 2012-02-28 - 12:06 HartmutStadie  
PDFpdf cError.pdf r2 r1 manage 11.0 K 2012-02-28 - 11:57 HartmutStadie  
PNGpng cError.png r6 r5 r4 r3 r2 manage 110.2 K 2012-02-28 - 12:21 HartmutStadie  
PNGpng cError_250.png r2 r1 manage 22.7 K 2012-02-28 - 12:06 HartmutStadie  
PDFpdf doubles_hitFitTtSemiLepEvent_MT_TOP_0Muo.pdf r2 r1 manage 14.0 K 2012-02-28 - 11:59 HartmutStadie  
PNGpng doubles_hitFitTtSemiLepEvent_MT_TOP_0Muo.png r4 r3 r2 r1 manage 139.3 K 2012-02-28 - 12:20 HartmutStadie  
PNGpng doubles_hitFitTtSemiLepEvent_MT_TOP_0Muo_250.png r2 r1 manage 30.9 K 2012-02-28 - 12:06 HartmutStadie  
PDFpdf fit_JES.pdf r1 manage 12.1 K 2012-02-23 - 16:30 HartmutStadie  
PNGpng fit_JES.png r3 r2 r1 manage 216.9 K 2012-02-24 - 11:25 HartmutStadie  
PDFpdf fit_JESPull.pdf r1 manage 12.1 K 2012-02-26 - 18:40 HartmutStadie  
PNGpng fit_JESPull.png r1 manage 195.0 K 2012-02-26 - 18:38 HartmutStadie  
PNGpng fit_JESPull_250.png r1 manage 31.4 K 2012-02-26 - 18:38 HartmutStadie  
PNGpng fit_JES_250.png r1 manage 33.8 K 2012-02-24 - 11:36 HartmutStadie  
PDFpdf fit_Mass.pdf r1 manage 11.8 K 2012-02-23 - 16:30 HartmutStadie  
PNGpng fit_Mass.png r3 r2 r1 manage 195.2 K 2012-02-24 - 11:25 HartmutStadie  
PDFpdf fit_MassPull.pdf r1 manage 12.2 K 2012-02-26 - 18:40 HartmutStadie  
PNGpng fit_MassPull.png r1 manage 196.1 K 2012-02-26 - 18:39 HartmutStadie  
PNGpng fit_MassPull_250.png r1 manage 31.0 K 2012-02-26 - 18:42 HartmutStadie  
PNGpng fit_Mass_250.png r1 manage 30.8 K 2012-02-24 - 11:36 HartmutStadie  
PDFpdf hadTopMass_weighted.pdf r2 r1 manage 19.1 K 2012-02-28 - 11:58 HartmutStadie  
PNGpng hadTopMass_weighted.png r4 r3 r2 r1 manage 177.1 K 2012-02-28 - 12:20 HartmutStadie  
PNGpng hadTopMass_weighted_250.png r2 r1 manage 36.7 K 2012-02-28 - 12:05 HartmutStadie  
PDFpdf hadTopRawMass.pdf r2 r1 manage 21.3 K 2012-02-28 - 12:00 HartmutStadie  
PNGpng hadTopRawMass.png r4 r3 r2 r1 manage 227.6 K 2012-02-28 - 12:12 HartmutStadie  
PNGpng hadTopRawMass_250.png r2 r1 manage 46.8 K 2012-02-28 - 12:04 HartmutStadie  
PDFpdf hadWRawMass.pdf r2 r1 manage 19.5 K 2012-02-28 - 11:58 HartmutStadie  
PNGpng hadWRawMass.png r4 r3 r2 r1 manage 201.5 K 2012-02-28 - 12:11 HartmutStadie  
PNGpng hadWRawMass_250.png r2 r1 manage 42.0 K 2012-02-28 - 12:04 HartmutStadie  
PDFpdf hadWRawMass_weighted.pdf r2 r1 manage 14.9 K 2012-02-28 - 11:57 HartmutStadie  
PNGpng hadWRawMass_weighted.png r4 r3 r2 r1 manage 186.2 K 2012-02-28 - 12:10 HartmutStadie  
PNGpng hadWRawMass_weighted_250.png r2 r1 manage 39.0 K 2012-02-28 - 12:04 HartmutStadie  
PDFpdf hitFitProb.pdf r2 r1 manage 15.5 K 2012-02-28 - 12:00 HartmutStadie  
PNGpng hitFitProb.png r4 r3 r2 r1 manage 160.3 K 2012-02-28 - 12:09 HartmutStadie  
PNGpng hitFitProb_250.png r2 r1 manage 36.7 K 2012-02-28 - 12:04 HartmutStadie  
PDFpdf leptonEta_event.pdf r2 r1 manage 15.5 K 2012-02-28 - 11:57 HartmutStadie  
PNGpng leptonEta_event.png r4 r3 r2 r1 manage 161.2 K 2012-02-28 - 12:08 HartmutStadie  
PNGpng leptonEta_event_250.png r2 r1 manage 35.7 K 2012-02-28 - 12:03 HartmutStadie  
PDFpdf leptonPt_event.pdf r2 r1 manage 17.2 K 2012-02-28 - 11:56 HartmutStadie  
PNGpng leptonPt_event.png r4 r3 r2 r1 manage 149.7 K 2012-02-28 - 12:07 HartmutStadie  
PNGpng leptonPt_event_250.png r2 r1 manage 31.2 K 2012-02-28 - 12:02 HartmutStadie  
PDFpdf mW_jes_cp.pdf r1 manage 16.1 K 2012-02-23 - 16:29 HartmutStadie  
PNGpng mW_jes_cp.png r3 r2 r1 manage 220.3 K 2012-02-24 - 11:27 HartmutStadie  
PNGpng mW_jes_cp_250.png r1 manage 41.6 K 2012-02-24 - 11:38 HartmutStadie  
PDFpdf mW_jes_un.pdf r1 manage 16.5 K 2012-02-23 - 16:29 HartmutStadie  
PNGpng mW_jes_un.png r3 r2 r1 manage 209.1 K 2012-02-24 - 11:27 HartmutStadie  
PNGpng mW_jes_un_250.png r1 manage 38.1 K 2012-02-24 - 11:39 HartmutStadie  
PDFpdf mW_jes_wp.pdf r1 manage 16.1 K 2012-02-23 - 16:29 HartmutStadie  
PNGpng mW_jes_wp.png r3 r2 r1 manage 219.8 K 2012-02-24 - 11:28 HartmutStadie  
PNGpng mW_jes_wp_250.png r1 manage 41.1 K 2012-02-24 - 11:39 HartmutStadie  
PDFpdf measurementComparison.pdf r1 manage 13.5 K 2012-02-24 - 12:50 MarkusSeidel  
PNGpng measurementComparison.png r1 manage 424.2 K 2012-02-24 - 12:50 MarkusSeidel  
PNGpng measurementComparison_500.png r1 manage 176.0 K 2012-02-24 - 12:52 MarkusSeidel  
PDFpdf mt_jes_cp.pdf r1 manage 14.6 K 2012-02-23 - 16:31 HartmutStadie  
PNGpng mt_jes_cp.png r3 r2 r1 manage 227.3 K 2012-02-24 - 11:26 HartmutStadie  
PNGpng mt_jes_cp_250.png r1 manage 43.4 K 2012-02-24 - 11:38 HartmutStadie  
PDFpdf mt_jes_un.pdf r1 manage 15.5 K 2012-02-23 - 16:30 HartmutStadie  
PNGpng mt_jes_un.png r3 r2 r1 manage 226.9 K 2012-02-24 - 11:26 HartmutStadie  
PNGpng mt_jes_un_250.png r1 manage 42.7 K 2012-02-24 - 11:38 HartmutStadie  
PDFpdf mt_jes_wp.pdf r1 manage 15.5 K 2012-02-23 - 16:29 HartmutStadie  
PNGpng mt_jes_wp.png r3 r2 r1 manage 205.9 K 2012-02-24 - 11:27 HartmutStadie  
PNGpng mt_jes_wp_250.png r1 manage 39.3 K 2012-02-24 - 11:38 HartmutStadie  
PDFpdf mt_mass_cp.pdf r1 manage 14.9 K 2012-02-23 - 16:31 HartmutStadie  
PNGpng mt_mass_cp.png r3 r2 r1 manage 236.3 K 2012-02-24 - 11:27 HartmutStadie  
PNGpng mt_mass_cp_250.png r1 manage 45.1 K 2012-02-24 - 11:38 HartmutStadie  
PDFpdf mt_mass_un.pdf r1 manage 15.8 K 2012-02-23 - 16:34 HartmutStadie  
PNGpng mt_mass_un.png r3 r2 r1 manage 235.6 K 2012-02-24 - 11:27 HartmutStadie  
PNGpng mt_mass_un_250.png r1 manage 44.6 K 2012-02-24 - 11:38 HartmutStadie  
PDFpdf mt_mass_wp.pdf r1 manage 15.8 K 2012-02-23 - 16:34 HartmutStadie  
PNGpng mt_mass_wp.png r3 r2 r1 manage 212.2 K 2012-02-24 - 11:27 HartmutStadie  
PNGpng mt_mass_wp_250.png r1 manage 40.3 K 2012-02-24 - 11:38 HartmutStadie  
PNGpng resulttext.png r3 r2 r1 manage 28.2 K 2012-02-24 - 11:46 HartmutStadie  
PNGpng systabletext.png r4 r3 r2 r1 manage 113.5 K 2012-02-24 - 13:22 HartmutStadie  
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