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| CMS-TOP-14-022 ; CERN-PH-EP-2015-234 | ||
| Measurement of the top quark mass using proton-proton data at $\sqrt{s} =$ 7 and 8 TeV | ||
| CMS Collaboration | ||
| 15 September 2015 | ||
| Phys. Rev. D 93 (2016) 072004 | ||
| Abstract: A new set of measurements of the top quark mass are presented, based on the proton-proton data recorded by the CMS experiment at the LHC at $\sqrt{s} =$ 8 TeV corresponding to a luminosity of 19.7 fb$^{-1}$. The top quark mass is measured using the lepton+jets, all-jets and dilepton decay channels, giving values of 172.35 $\pm$ 0.16 (stat) $\pm$ 0.48 (syst) GeV, 172.32 $\pm$ 0.25 (stat) $\pm$ 0.59 (syst) GeV, and 172.82 $\pm$ 0.19 (stat) $\pm$ 1.22 (syst) GeV, respectively. When combined with the published CMS results at $\sqrt{s} =$ 7 TeV, they provide a top quark mass measurement of 172.44 $\pm$ 0.13 (stat) $\pm$ 0.47 (syst) GeV. The top quark mass is also studied as a function of the event kinematical properties in the lepton+jets decay channel. No indications of a kinematic bias are observed and the collision data are consistent with a range of predictions from current theoretical models of $ \mathrm{ t \bar{t} } $ production. | ||
| Links: e-print arXiv:1509.04044 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; HepData record ; CADI line (restricted) ; | ||
| Figures | |
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Figure 1:
Distributions for the lepton+jets channel of (top left) lepton $ {p_{\mathrm {T}}} $, (top right) missing transverse energy, (bottom left) leading jet $ {p_{\mathrm {T}}} $, (bottom right) second-leading jet $ {p_{\mathrm {T}}} $ for data and simulation, summed over all channels and normalized by luminosity. The vertical bars show the statistical uncertainty and the hatched bands show the statistical and systematic uncertainties added in quadrature. The lower portion of each panel shows the ratio of the yields between the collision data and the simulation. |
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Figure 1-a:
Distribution for the lepton+jets channel of lepton $ {p_{\mathrm {T}}} $ for data and simulation, summed over all channels and normalized by luminosity. The vertical bars show the statistical uncertainty and the hatched bands show the statistical and systematic uncertainties added in quadrature. The lower portion of each panel shows the ratio of the yields between the collision data and the simulation. |
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Figure 1-b:
Distribution for the lepton+jets channel of missing transverse energy for data and simulation, summed over all channels and normalized by luminosity. The vertical bars show the statistical uncertainty and the hatched bands show the statistical and systematic uncertainties added in quadrature. The lower portion of each panel shows the ratio of the yields between the collision data and the simulation. |
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Figure 1-c:
Distribution for the lepton+jets channel of leading jet $ {p_{\mathrm {T}}} $ for data and simulation, summed over all channels and normalized by luminosity. The vertical bars show the statistical uncertainty and the hatched bands show the statistical and systematic uncertainties added in quadrature. The lower portion of each panel shows the ratio of the yields between the collision data and the simulation. |
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Figure 1-d:
Distribution for the lepton+jets channel of second-leading jet $ {p_{\mathrm {T}}} $ for data and simulation, summed over all channels and normalized by luminosity. The vertical bars show the statistical uncertainty and the hatched bands show the statistical and systematic uncertainties added in quadrature. The lower portion of each panel shows the ratio of the yields between the collision data and the simulation. |
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Figure 2:
Distributions for the dilepton channel: (top left) leading lepton $ {p_{\mathrm {T}}} $, (top right) second-leading lepton $ {p_{\mathrm {T}}} $, (bottom left) leading jet $ {p_{\mathrm {T}}} $, (bottom right) second-leading jet $ {p_{\mathrm {T}}} $ for data and simulation, summed over all channels and normalized by luminosity. The vertical bars show the statistical uncertainty and the hatched bands show the statistical and systematic uncertainties added in quadrature. The lower portion of each panel shows the ratio of the yields between the collision data and the simulation. |
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Figure 2-a:
Dilepton channel: leading lepton $ {p_{\mathrm {T}}} $ for data and simulation, summed over all channels and normalized by luminosity. The vertical bars show the statistical uncertainty and the hatched bands show the statistical and systematic uncertainties added in quadrature. The lower portion of each panel shows the ratio of the yields between the collision data and the simulation. |
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Figure 2-b:
Dilepton channel: second-leading lepton $ {p_{\mathrm {T}}} $ for data and simulation, summed over all channels and normalized by luminosity. The vertical bars show the statistical uncertainty and the hatched bands show the statistical and systematic uncertainties added in quadrature. The lower portion of each panel shows the ratio of the yields between the collision data and the simulation. |
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Figure 2-c:
Dilepton channel: leading jet $ {p_{\mathrm {T}}} $ for data and simulation, summed over all channels and normalized by luminosity. The vertical bars show the statistical uncertainty and the hatched bands show the statistical and systematic uncertainties added in quadrature. The lower portion of each panel shows the ratio of the yields between the collision data and the simulation. |
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Figure 2-d:
Dilepton channel: second-leading jet $ {p_{\mathrm {T}}} $ for data and simulation, summed over all channels and normalized by luminosity. The vertical bars show the statistical uncertainty and the hatched bands show the statistical and systematic uncertainties added in quadrature. The lower portion of each panel shows the ratio of the yields between the collision data and the simulation. |
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Figure 3:
Reconstructed masses of (top left) the W bosons decaying to $ {\mathrm {q}} {\overline {\mathrm {q}}} $ pairs and (top right) the corresponding top quarks, prior to the kinematic fitting to the $ {\mathrm {t}\overline {\mathrm {t}}} $ hypothesis. Panels (bottom left) and (bottom right) show, respectively, the reconstructed W boson masses and the fitted top quark masses after the goodness-of-fit selection and the weighting by $P_{\mathrm {gof} }$. The total number of permutations found in simulation is normalized to be the same as the total number of permutations observed in data. The vertical bars show the statistical uncertainty and the hatched bands show the statistical and systematic uncertainties added in quadrature. The lower portion of each panel shown the ratio of the yields between the collision data and the simulation. |
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Figure 3-a:
Reconstructed mass of the W bosons decaying to $ {\mathrm {q}} {\overline {\mathrm {q}}} $ pairs, prior to the kinematic fitting to the $ {\mathrm {t}\overline {\mathrm {t}}} $ hypothesis. The total number of permutations found in simulation is normalized to be the same as the total number of permutations observed in data. The vertical bars show the statistical uncertainty and the hatched bands show the statistical and systematic uncertainties added in quadrature. The lower portion of the panel shows the ratio of the yields between the collision data and the simulation. |
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Figure 3-b:
Reconstructed mass of the top quarks corresponding to the W bosons decaying to $ {\mathrm {q}} {\overline {\mathrm {q}}} $ pairs, prior to the kinematic fitting to the $ {\mathrm {t}\overline {\mathrm {t}}} $ hypothesis. The total number of permutations found in simulation is normalized to be the same as the total number of permutations observed in data. The vertical bars show the statistical uncertainty and the hatched bands show the statistical and systematic uncertainties added in quadrature. The lower portion of the panel shows the ratio of the yields between the collision data and the simulation. |
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Figure 3-c:
Reconstructed W boson masses after the goodness-of-fit selection and the weighting by $P_{\mathrm {gof} }$. The total number of permutations found in simulation is normalized to be the same as the total number of permutations observed in data. The vertical bars show the statistical uncertainty and the hatched bands show the statistical and systematic uncertainties added in quadrature. The lower portion of the panel shows the ratio of the yields between the collision data and the simulation. |
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Figure 3-d:
Fitted top quark masses after the goodness-of-fit selection and the weighting by $P_{\mathrm {gof} }$. The total number of permutations found in simulation is normalized to be the same as the total number of permutations observed in data. The vertical bars show the statistical uncertainty and the hatched bands show the statistical and systematic uncertainties added in quadrature. The lower portion of the panel shows the ratio of the yields between the collision data and the simulation. |
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Figure 4:
The two-dimensional likelihood ($-2 \Delta \log\left (\mathcal {L}\right )$) for the lepton+jets channel for the 2D, hybrid, and 1D fits. The thick (thin) ellipses correspond to contours of $-2 \Delta \log\left (\mathcal {L}\right ) =$ 1 (4) allowing the construction of the one (two) $\sigma $ statistical intervals of $ {m_{ {\mathrm {t}} }} $. For the 1D fit, the thick and thin lines correspond to the one and two $\sigma $ statistical uncertainties, respectively. |
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Figure 5:
Distributions of (top left) the reconstructed top quark mass from the kinematic fit, (top right) the average reconstructed W boson mass, (bottom left) the goodness-of-fit probability, and (bottom right) the separation of the two b quark jets for the all-jets channel. The simulated $ {\mathrm {t}\overline {\mathrm {t}}} $ signal and the background from the control sample are normalized to data. The value of $ {m_{ {\mathrm {t}} }} $ used in the simulation is 172.5 GeV and the nominal jet energy scale is applied. The vertical bars show the statistical uncertainty and the hatched bands show the statistical and systematic uncertainties added in quadrature. The lower portion of each panel shows the ratio of the yields between the collision data and the simulation. |
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Figure 5-a:
Distribution of the reconstructed top quark mass from the kinematic fit for the all-jets channel. The simulated $ {\mathrm {t}\overline {\mathrm {t}}} $ signal and the background from the control sample are normalized to data. The value of $ {m_{ {\mathrm {t}} }} $ used in the simulation is 172.5 GeV and the nominal jet energy scale is applied. The vertical bars show the statistical uncertainty and the hatched bands show the statistical and systematic uncertainties added in quadrature. The lower portion of each panel shows the ratio of the yields between the collision data and the simulation. |
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Figure 5-b:
Distribution of the average reconstructed W boson mass for the all-jets channel. The simulated $ {\mathrm {t}\overline {\mathrm {t}}} $ signal and the background from the control sample are normalized to data. The value of $ {m_{ {\mathrm {t}} }} $ used in the simulation is 172.5 GeV and the nominal jet energy scale is applied. The vertical bars show the statistical uncertainty and the hatched bands show the statistical and systematic uncertainties added in quadrature. The lower portion of each panel shows the ratio of the yields between the collision data and the simulation. |
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Figure 5-c:
Distribution of the goodness-of-fit probability for the all-jets channel. The simulated $ {\mathrm {t}\overline {\mathrm {t}}} $ signal and the background from the control sample are normalized to data. The value of $ {m_{ {\mathrm {t}} }} $ used in the simulation is 172.5 GeV and the nominal jet energy scale is applied. The vertical bars show the statistical uncertainty and the hatched bands show the statistical and systematic uncertainties added in quadrature. The lower portion of each panel shows the ratio of the yields between the collision data and the simulation. |
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Figure 5-d:
Distribution of the separation of the two b quark jets for the all-jets channel. The simulated $ {\mathrm {t}\overline {\mathrm {t}}} $ signal and the background from the control sample are normalized to data. The value of $ {m_{ {\mathrm {t}} }} $ used in the simulation is 172.5 GeV and the nominal jet energy scale is applied. The vertical bars show the statistical uncertainty and the hatched bands show the statistical and systematic uncertainties added in quadrature. The lower portion of each panel shows the ratio of the yields between the collision data and the simulation. |
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Figure 6:
The two-dimensional likelihood ($-2 \Delta \log\left (\mathcal {L}\right )$) for the all-jets channel for the 2D, hybrid, and 1D fits. The thick (thin) ellipses correspond to contours of $-2 \Delta \log\left (\mathcal {L}\right ) =$ 1 (4) allowing the construction of the one (two) $\sigma $ statistical intervals of $ {m_{ {\mathrm {t}} }} $. For the 1D fit, the thick and thin lines correspond to the one and two $\sigma $ statistical uncertainties, respectively. |
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Figure 7:
Distribution of $m_{ {\mathrm {t}} }^{\mathrm {AMWT}}$ for the collision and simulated data with $ {m_{ {\mathrm {t}} }} =$ 172.5 GeV. The vertical bars show the statistical uncertainty and the hatched bands show the statistical and systematic uncertainties added in quadrature. The lower section of the plot shows the ratio of the yields between the collision data and the simulation. |
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Figure 8:
Plot of the negative log-likelihood for data for the dilepton analysis. The continuous line represents a parabolic fit to the points. |
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Figure 9:
Measurements of $ {m_{ {\mathrm {t}} }} $ as a function of the transverse momentum of the hadronically decaying top quark ($ {p_{\mathrm {T}}} ^{\rm {t,had}}$), the invariant mass of the $ {\mathrm {t}\overline {\mathrm {t}}} $ system ($m_{ {\mathrm {t}\overline {\mathrm {t}}} }$), the transverse momentum of the $ {\mathrm {t}\overline {\mathrm {t}}} $ system ($ {p_{\mathrm {T}}} ^{ {\mathrm {t}\overline {\mathrm {t}}} }$), and the number of jets with $ {p_{\mathrm {T}}} >$ 30 GeV. The filled circles represent the data, and the other symbols are for the simulations. For reasons of clarity the horizontal error bars are shown only for the data points and each of the simulations is shown as a single offset point with a vertical error bar representing its statistical uncertainty. The statistical uncertainty of the data is displayed by the inner error bars. For the outer error bars, the systematic uncertainties are added in quadrature. The open circles correspond to MadGraph with the PYTHIA Z2* tune, the open squares to MadGraph with the PYTHIA Perugia 2011 tune, and the open triangles represent MadGraph with the PYTHIA Perugia 2011 noCR tune. The open diamonds correspond to POWHEG with the PYTHIA Z2* tune and the open crosses correspond to POWHEG with HERWIG 6. The filled stars are for MC@NLO with HERWIG 6 and the open stars are for SHERPA. |
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Figure 9-a:
Measurement of $ {m_{ {\mathrm {t}} }} $ as a function of the transverse momentum of the hadronically decaying top quark ($ {p_{\mathrm {T}}} ^{\rm {t,had}}$). The filled circles represent the data, and the other symbols are for the simulations. For reasons of clarity the horizontal error bars are shown only for the data points and each of the simulations is shown as a single offset point with a vertical error bar representing its statistical uncertainty. The statistical uncertainty of the data is displayed by the inner error bars. For the outer error bars, the systematic uncertainties are added in quadrature. The open circles correspond to MadGraph with the PYTHIA Z2* tune, the open squares to MadGraph with the PYTHIA Perugia 2011 tune, and the open triangles represent MadGraph with the PYTHIA Perugia 2011 noCR tune. The open diamonds correspond to POWHEG with the PYTHIA Z2* tune and the open crosses correspond to POWHEG with HERWIG 6. The filled stars are for MC@NLO with HERWIG 6 and the open stars are for SHERPA. |
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Figure 9-b:
Measurement of the invariant mass of the $ {\mathrm {t}\overline {\mathrm {t}}} $ system ($m_{ {\mathrm {t}\overline {\mathrm {t}}} }$). The filled circles represent the data, and the other symbols are for the simulations. For reasons of clarity the horizontal error bars are shown only for the data points and each of the simulations is shown as a single offset point with a vertical error bar representing its statistical uncertainty. The statistical uncertainty of the data is displayed by the inner error bars. For the outer error bars, the systematic uncertainties are added in quadrature. The open circles correspond to MadGraph with the PYTHIA Z2* tune, the open squares to MadGraph with the PYTHIA Perugia 2011 tune, and the open triangles represent MadGraph with the PYTHIA Perugia 2011 noCR tune. The open diamonds correspond to POWHEG with the PYTHIA Z2* tune and the open crosses correspond to POWHEG with HERWIG 6. The filled stars are for MC@NLO with HERWIG 6 and the open stars are for SHERPA. |
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Figure 9-c:
Measurement of the transverse momentum of the $ {\mathrm {t}\overline {\mathrm {t}}} $ system ($ {p_{\mathrm {T}}} ^{ {\mathrm {t}\overline {\mathrm {t}}} }$). The filled circles represent the data, and the other symbols are for the simulations. For reasons of clarity the horizontal error bars are shown only for the data points and each of the simulations is shown as a single offset point with a vertical error bar representing its statistical uncertainty. The statistical uncertainty of the data is displayed by the inner error bars. For the outer error bars, the systematic uncertainties are added in quadrature. The open circles correspond to MadGraph with the PYTHIA Z2* tune, the open squares to MadGraph with the PYTHIA Perugia 2011 tune, and the open triangles represent MadGraph with the PYTHIA Perugia 2011 noCR tune. The open diamonds correspond to POWHEG with the PYTHIA Z2* tune and the open crosses correspond to POWHEG with HERWIG 6. The filled stars are for MC@NLO with HERWIG 6 and the open stars are for SHERPA. |
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Figure 9-d:
Measurement of the number of jets with $ {p_{\mathrm {T}}} >$ 30 GeV. The filled circles represent the data, and the other symbols are for the simulations. For reasons of clarity the horizontal error bars are shown only for the data points and each of the simulations is shown as a single offset point with a vertical error bar representing its statistical uncertainty. The statistical uncertainty of the data is displayed by the inner error bars. For the outer error bars, the systematic uncertainties are added in quadrature. The open circles correspond to MadGraph with the PYTHIA Z2* tune, the open squares to MadGraph with the PYTHIA Perugia 2011 tune, and the open triangles represent MadGraph with the PYTHIA Perugia 2011 noCR tune. The open diamonds correspond to POWHEG with the PYTHIA Z2* tune and the open crosses correspond to POWHEG with HERWIG 6. The filled stars are for MC@NLO with HERWIG 6 and the open stars are for SHERPA. |
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Figure 10:
Measurements of $ {m_{ {\mathrm {t}} }} $ as a function of the $ {p_{\mathrm {T}}} $ of the b jet assigned to the hadronic decay branch ($ {p_{\mathrm {T}}} ^{\rm {b,had}}$), the pseudorapidity of the b jet assigned to the hadronic decay branch ($\left |\eta ^{\rm b,had}\right |$), the $\Delta R$ between the b jets ($\Delta R_{ { {\mathrm {b}} {\overline {\mathrm {b}}} } }$), and the $\Delta R$ between the light-quark jets ($\Delta R_{ { {\mathrm {q}} {\overline {\mathrm {q}}} } }$). The filled circles represent the data, and the other symbols are for the simulations. For reasons of clarity the horizontal error bars are shown only for the data points and each of the simulations is shown as a single offset point with a vertical error bar representing its statistical uncertainty. The statistical uncertainty of the data is displayed by the inner error bars. For the outer error bars, the systematic uncertainties are added in quadrature.The open circles correspond to MadGraph with the PYTHIA Z2* tune, the open squares to MadGraph with the PYTHIA Perugia 2011 tune, and the open triangles represent MadGraph with the PYTHIA Perugia 2011 noCR tune. The open diamonds correspond to POWHEG with the PYTHIA Z2* tune and the open crosses correspond to POWHEG with HERWIG 6. The filled stars are for MC@NLO with HERWIG 6 and the open stars are for SHERPA. |
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Figure 10-a:
Measurement of $ {m_{ {\mathrm {t}} }} $ as a function of the $ {p_{\mathrm {T}}} $ of the b jet assigned to the hadronic decay branch ($ {p_{\mathrm {T}}} ^{\rm {b,had}}$). The filled circles represent the data, and the other symbols are for the simulations. For reasons of clarity the horizontal error bars are shown only for the data points and each of the simulations is shown as a single offset point with a vertical error bar representing its statistical uncertainty. The statistical uncertainty of the data is displayed by the inner error bars. For the outer error bars, the systematic uncertainties are added in quadrature.The open circles correspond to MadGraph with the PYTHIA Z2* tune, the open squares to MadGraph with the PYTHIA Perugia 2011 tune, and the open triangles represent MadGraph with the PYTHIA Perugia 2011 noCR tune. The open diamonds correspond to POWHEG with the PYTHIA Z2* tune and the open crosses correspond to POWHEG with HERWIG 6. The filled stars are for MC@NLO with HERWIG 6 and the open stars are for SHERPA. |
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Figure 10-b:
Measurement of $ {m_{ {\mathrm {t}} }} $ as a function of the pseudorapidity of the b jet assigned to the hadronic decay branch ($\left |\eta ^{\rm b,had}\right |$). The filled circles represent the data, and the other symbols are for the simulations. For reasons of clarity the horizontal error bars are shown only for the data points and each of the simulations is shown as a single offset point with a vertical error bar representing its statistical uncertainty. The statistical uncertainty of the data is displayed by the inner error bars. For the outer error bars, the systematic uncertainties are added in quadrature.The open circles correspond to MadGraph with the PYTHIA Z2* tune, the open squares to MadGraph with the PYTHIA Perugia 2011 tune, and the open triangles represent MadGraph with the PYTHIA Perugia 2011 noCR tune. The open diamonds correspond to POWHEG with the PYTHIA Z2* tune and the open crosses correspond to POWHEG with HERWIG 6. The filled stars are for MC@NLO with HERWIG 6 and the open stars are for SHERPA. |
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Figure 10-c:
Measurement of $ {m_{ {\mathrm {t}} }} $ as a function of the $\Delta R$ between the b jets ($\Delta R_{ { {\mathrm {b}} {\overline {\mathrm {b}}} } }$). The filled circles represent the data, and the other symbols are for the simulations. For reasons of clarity the horizontal error bars are shown only for the data points and each of the simulations is shown as a single offset point with a vertical error bar representing its statistical uncertainty. The statistical uncertainty of the data is displayed by the inner error bars. For the outer error bars, the systematic uncertainties are added in quadrature.The open circles correspond to MadGraph with the PYTHIA Z2* tune, the open squares to MadGraph with the PYTHIA Perugia 2011 tune, and the open triangles represent MadGraph with the PYTHIA Perugia 2011 noCR tune. The open diamonds correspond to POWHEG with the PYTHIA Z2* tune and the open crosses correspond to POWHEG with HERWIG 6. The filled stars are for MC@NLO with HERWIG 6 and the open stars are for SHERPA. |
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Figure 10-d:
Measurement of $ {m_{ {\mathrm {t}} }} $ as a function of the $\Delta R$ between the light-quark jets ($\Delta R_{ { {\mathrm {q}} {\overline {\mathrm {q}}} } }$). The filled circles represent the data, and the other symbols are for the simulations. For reasons of clarity the horizontal error bars are shown only for the data points and each of the simulations is shown as a single offset point with a vertical error bar representing its statistical uncertainty. The statistical uncertainty of the data is displayed by the inner error bars. For the outer error bars, the systematic uncertainties are added in quadrature.The open circles correspond to MadGraph with the PYTHIA Z2* tune, the open squares to MadGraph with the PYTHIA Perugia 2011 tune, and the open triangles represent MadGraph with the PYTHIA Perugia 2011 noCR tune. The open diamonds correspond to POWHEG with the PYTHIA Z2* tune and the open crosses correspond to POWHEG with HERWIG 6. The filled stars are for MC@NLO with HERWIG 6 and the open stars are for SHERPA. |
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Figure 11:
Systematic uncertainty correlations for mass measurements in the lepton+jets and all-jets channels. Each point represents a single systematic uncertainty taken from Tables 1 and 2. Left panel: for the 2D lepton+jets and 1D all-jets measurements; Right panel: for the hybrid lepton+jets and the 1D all-jets measurements. The filled circles correspond to the systematic uncertainties which show a positive correlation between the two fit methods and the open circles to the systematic terms which show a negative correlation. The points shown as filled squares are those for which the systematic estimation is dominated by a statistical uncertainty, so no clear categorization is possible. The vertical and horizontal error bars correspond to the statistical uncertainties in the systematic uncertainties. |
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Figure 11-a:
Systematic uncertainty correlations for mass measurements in the lepton+jets and all-jets channels. Each point represents a single systematic uncertainty taken from Tables 1 and 2 for the 2D lepton+jets and 1D all-jets measurements. The filled circles correspond to the systematic uncertainties which show a positive correlation between the two fit methods and the open circles to the systematic terms which show a negative correlation. The points shown as filled squares are those for which the systematic estimation is dominated by a statistical uncertainty, so no clear categorization is possible. The vertical and horizontal error bars correspond to the statistical uncertainties in the systematic uncertainties. |
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Figure 11-b:
Systematic uncertainty correlations for mass measurements in the lepton+jets and all-jets channels. Each point represents a single systematic uncertainty taken from Tables 1 and 2 for the hybrid lepton+jets and the 1D all-jets measurements. The filled circles correspond to the systematic uncertainties which show a positive correlation between the two fit methods and the open circles to the systematic terms which show a negative correlation. The points shown as filled squares are those for which the systematic estimation is dominated by a statistical uncertainty, so no clear categorization is possible. The vertical and horizontal error bars correspond to the statistical uncertainties in the systematic uncertainties. |
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Figure 12:
Summary of the CMS $ {m_{ {\mathrm {t}} }} $ measurements and their combination. The thick error bars show the statistical uncertainty and the thin error bars show the total uncertainty. Also shown are the current Tevatron [8] and world average [7] combinations. |
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Figure 13:
Results of the BLUE combining procedure on the CMS measurements showing (left) the combination coefficients, and (right) the pulls for each contribution. |
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Figure 13-a:
Results of the BLUE combining procedure on the CMS measurements showing the combination coefficients for each contribution. |
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Figure 13-b:
Results of the BLUE combining procedure on the CMS measurements showing the pulls for each contribution. |
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Figure 14:
The combined $\sqrt {s} =$ 7 and 8 TeV measurements of $ {m_{ {\mathrm {t}} }} $ for each of the $ {\mathrm {t}\overline {\mathrm {t}}} $ decay channels. |
| Tables | |
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Table 1:
Category breakdown of the systematic uncertainties for the 2D, 1D, and hybrid measurements in the lepton+jets channel. Each term has been estimated using the procedures described in Section 6. The uncertainties are expressed in GeV and the signs are taken from the $+1\sigma $ shift in the value of the quantity. Thus a positive sign indicates an increase in the value of $m_{ {\mathrm {t}} }$ or the JSF and a negative sign indicates a decrease. With the exception of the flavor-dependent JEC terms (see Section 6), the total systematic uncertainty is obtained from the sum in quadrature of the individual systematic uncertainties. |
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Table 2:
Category breakdown of the systematic uncertainties for the 2D, 1D and hybrid measurements in the all-jets channel. Each term has been estimated using the procedures described in Section 6. The uncertainties are expressed in GeV and the signs are taken from the $+1\sigma $ shift in the value of the quantity. Thus a positive sign indicates an increase in the value of $m_{ {\mathrm {t}} }$ or the JSF and a negative sign indicates a decrease. With the exception of the flavor-dependent JEC terms (see Section 6), the total systematic uncertainty is obtained from the sum in quadrature of the individual systematic uncertainties. |
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Table 3:
Category breakdown of the systematic uncertainties for the AMWT measurement in the dilepton channel. Each term has been estimated using the procedures described in Section 6. The uncertainties are expressed in GeV and the signs are taken from the $+1\sigma $ shift in the value of the quantity. Thus a positive sign indicates an increase in the value of $m_{ {\mathrm {t}} }$ and a negative sign indicates a decrease. With the exception of the flavor-dependent JEC terms (see Section 6), the total systematic uncertainty is obtained from the sum in quadrature of the individual systematic uncertainties. |
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Table 4:
CMS measurements of the top quark mass using the data recorded at $\sqrt {s} =$ 7 TeV. |
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Table 5:
Comparison of different simulations and the data. The summed $\chi ^{2}$ values and number of standard deviations are computed for the 27 points entering Figs. 9 and 10 assuming two-sided Gaussian statistics. |
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Table 6:
Nominal correlation coefficients for the systematic uncertainties. The term $\rho _{\rm chan}$ is the correlation factor for measurements in the same top quark decay channel, but different years and the term $\rho _{\rm year}$ is the correlation between measurements in different channels from the same year. |
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Table 7:
Combination results for the permutations of the 2D, 1D, and hybrid measurements. The permutation order is defined to be lepton+jets:all-jets:dilepton, thus 211 corresponds to the 2D lepton+jets:1D all-jets:AMWT dilepton combination. |
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Table 8:
Correlations between input measurements. The elements in the table are labelled according to the analysis they correspond to (rows and columns read as 2010, 2011, 2012 followed by the $ {\mathrm {t}\overline {\mathrm {t}}} $ decay channel name). |
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Table 9:
Category breakdown of systematic uncertainties for the combined mass result. The uncertainties are expressed in GeV. |
| Summary |
|
A new set of measurements of the top quark mass has been presented, based on the data recorded by the CMS experiment at the LHC at $\sqrt{s} =$ 8 TeV during 2012, and corresponding to a luminosity of 19.7 fb$^{-1}$. The top quark mass has been measured in the lepton+jets, all-jets and dilepton decay channels, giving values of 172.32 $\pm$ 0.25 (stat) $\pm$ 0.59 (syst) GeV, and 172.82 $\pm$ 0.19 (stat) $\pm$ 1.22 (syst) GeV, respectively. Individually, these constitute the most precise measurements in each of the decay channels studied. When combined with the published CMS results at $\sqrt{s} =$ 7 TeV, a top quark mass measurement of is obtained. This is the most precise measurement of $m_{\text{top}}$ to date, with a total uncertainty of 0.48 GeV, and it supersedes all of the previous CMS measurements of the top quark mass. The top quark mass has also been studied as a function of the event kinematical properties in the lepton+jets channel. No indications of a kinematical bias in the measurements is observed and the data are consistent with a range of predictions from current theoretical models of $ \mathrm{ t \bar{t} } $ production. |
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