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| CMS-PAS-HIG-17-026 | ||
| Search for $\mathrm{t\bar{t}H}$ production in the $\mathrm{H\rightarrow b\bar{b}}$ decay channel with leptonic $\mathrm{t\bar{t}}$ decays in proton-proton collisions at $\sqrt{s}= $ 13 TeV with the CMS detector | ||
| CMS Collaboration | ||
| March 2018 | ||
| Abstract: A search for the associated production of a standard model Higgs boson with a top quark-antiquark pair ($\mathrm{t\bar{t}H}$) in proton-proton collisions at a center-of-mass energy $\sqrt{s}= $ 13 TeV is presented. The data correspond to an integrated luminosity of 35.9 fb$^{-1}$ recorded with the CMS detector at the CERN LHC in 2016. Candidate $\mathrm{t\bar{t}H}$ events are selected that contain either one or two electrons or muons from the $\mathrm{t\bar{t}}$ decays, and are categorized according to the number of jets. Multivariate techniques are employed to categorize further the events and eventually discriminate between signal and background events. The results are characterized by an observed $\mathrm{t\bar{t}H}$ signal strength relative to the standard model cross section, $\mu = \sigma/\sigma_{\mathrm{SM}}$, under the assumption of $m_{\mathrm{H}} = $ 125 GeV. A combined fit of multivariate discriminant distributions in all categories results in an observed (expected) upper limit of $\mu < $ 1.5 (0.9) at the 95% confidence level, and a best fit value of $\mu = $ 0.72 $\pm$ 0.45, corresponding to an observed (expected) significance of 1.6 (2.2) standard deviations. | ||
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Links:
CDS record (PDF) ;
inSPIRE record ;
CADI line (restricted) ;
These preliminary results are superseded in this paper, JHEP 03 (2019) 026. The superseded preliminary plots can be found here. |
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| Figures | |
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Figure 1:
Representative leading-order Feynman diagrams for $ \mathrm{ t\bar{t} H } $ production, including the subsequent decay of the Higgs boson into a b quark-antiquark pair, and the decay of the top quark-antiquark pair into final states with either one (single-lepton channel, left) or two (dilepton channel, right) electrons or muons. |
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Figure 1-a:
Representative leading-order Feynman diagram for $ \mathrm{ t\bar{t} H } $ production, including the subsequent decay of the Higgs boson into a b quark-antiquark pair, and the decay of the top quark-antiquark pair into final states with either one (single-lepton channel, left) or two (dilepton channel, right) electrons or muons. |
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Figure 1-b:
Representative leading-order Feynman diagram for $ \mathrm{ t\bar{t} H } $ production, including the subsequent decay of the Higgs boson into a b quark-antiquark pair, and the decay of the top quark-antiquark pair into final states with either one (single-lepton channel, left) or two (dilepton channel, right) electrons or muons. |
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Figure 2:
Jet (left) and b-tagged jet (right) multiplicity after the baseline event selection in the single-lepton channel. The uncertainty bands correspond to the total statistic and systematic uncertainties (excluding uncertainties that affect only the rate of the distribution) added in quadrature. |
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Figure 2-a:
Jet multiplicity after the baseline event selection in the single-lepton channel. The uncertainty bands correspond to the total statistic and systematic uncertainties (excluding uncertainties that affect only the rate of the distribution) added in quadrature. |
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Figure 2-b:
b-tagged jet multiplicity after the baseline event selection in the single-lepton channel. The uncertainty bands correspond to the total statistic and systematic uncertainties (excluding uncertainties that affect only the rate of the distribution) added in quadrature. |
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Figure 3:
Jet (left) and b-tagged jet (right) multiplicity after the baseline event selection in the dilepton channel. The uncertainty bands correspond to the total statistical and systematic uncertainties (excluding uncertainties that affect only the rate of the distribution) added in quadrature. |
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Figure 3-a:
Jet multiplicity after the baseline event selection in the dilepton channel. The uncertainty bands correspond to the total statistical and systematic uncertainties (excluding uncertainties that affect only the rate of the distribution) added in quadrature. |
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Figure 3-b:
b-tagged jet multiplicity after the baseline event selection in the dilepton channel. The uncertainty bands correspond to the total statistical and systematic uncertainties (excluding uncertainties that affect only the rate of the distribution) added in quadrature. |
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Figure 4:
Final discriminant shapes in the single-lepton (SL) channel before the fit to data: DNN discriminant in the jet-process categories with $\geq $6 jets-$ \mathrm{ t\bar{t} H } $ (top left); 5 jets-$ \mathrm{ t \bar{t} } + \mathrm{ b \bar{b} } $ (top right); 4 jets-$ \mathrm{ t \bar{t} } + \text{lf} $ (bottom left) and $\geq $6 jets-$ \mathrm{ t \bar{t} } + \mathrm{ c \bar{c} } $ (bottom right). The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. The distributions observed in data (markers) are overlayed. |
png pdf |
Figure 4-a:
Final discriminant shape in the single-lepton (SL) channel before the fit to data: DNN discriminant in the jet-process category with $\geq $6 jets-$ \mathrm{ t\bar{t} H } $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. The distributions observed in data (markers) are overlayed. |
png pdf |
Figure 4-b:
Final discriminant shape in the single-lepton (SL) channel before the fit to data: DNN discriminant in the jet-process category with 5 jets-$ \mathrm{ t \bar{t} } + \mathrm{ b \bar{b} } $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. The distributions observed in data (markers) are overlayed. |
png pdf |
Figure 4-c:
Final discriminant shape in the single-lepton (SL) channel before the fit to data: DNN discriminant in the jet-process category with 4 jets-$ \mathrm{ t \bar{t} } + \text{lf} $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. The distributions observed in data (markers) are overlayed. |
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Figure 4-d:
Final discriminant shape in the single-lepton (SL) channel before the fit to data: DNN discriminant in the jet-process category with $\geq $6 jets-$ \mathrm{ t \bar{t} } + \mathrm{ c \bar{c} } $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. The distributions observed in data (markers) are overlayed. |
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Figure 5:
Final discriminant shapes in the dilepton (DL) channel before the fit to data: BDT discriminant in the analysis category with ($\geq$4 jets, 3 b-tags) (top row) and MEM discriminant in the analysis categories with ($\geq$4 jets, $\geq$4 b-tags) (bottom row) with low (left) and high (right) BDT output. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. The distributions observed in data (markers) are overlayed. |
png pdf |
Figure 5-a:
Final discriminant shape in the dilepton (DL) channel before the fit to data: BDT discriminant in the analysis category with ($\geq$4 jets, 3 b-tags). The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. The distributions observed in data (markers) are overlayed. |
png pdf |
Figure 5-b:
Final discriminant shape in the dilepton (DL) channel before the fit to data: MEM discriminant in the analysis categories with ($\geq$4 jets, $\geq$4 b-tags) with low BDT output. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. The distributions observed in data (markers) are overlayed. |
png pdf |
Figure 5-c:
Final discriminant shape in the dilepton (DL) channel before the fit to data: MEM discriminant in the analysis categories with ($\geq$4 jets, $\geq$4 b-tags) with high BDT output. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. The distributions observed in data (markers) are overlayed. |
png pdf |
Figure 6:
Final discriminant shapes in the single-lepton (SL) channel after the fit to data: DNN discriminant in the jet-process categories with $\geq $6 jets-$ \mathrm{ t\bar{t} H } $ (top left); 5 jets-$ \mathrm{ t \bar{t} } + \mathrm{ b \bar{b} } $ (top right); 4 jets-$ \mathrm{ t \bar{t} } + \text{lf} $ (bottom left) and $\geq $6 jets-$ \mathrm{ t \bar{t} } + \mathrm{ c \bar{c} } $ (bottom right). The error bands include the total uncertainty after the fit to data. The distributions observed in data (markers) are overlayed. |
png pdf |
Figure 6-a:
Final discriminant shape in the single-lepton (SL) channel after the fit to data: DNN discriminant in the jet-process categories with $\geq $6 jets-$ \mathrm{ t\bar{t} H } $. The error bands include the total uncertainty after the fit to data. The distribution observed in data (markers) is overlayed. |
png pdf |
Figure 6-b:
Final discriminant shape in the single-lepton (SL) channel after the fit to data: DNN discriminant in the jet-process categories with 5 jets-$ \mathrm{ t \bar{t} } + \mathrm{ b \bar{b} } $. The error bands include the total uncertainty after the fit to data. The distribution observed in data (markers) is overlayed. |
png pdf |
Figure 6-c:
Final discriminant shape in the single-lepton (SL) channel after the fit to data: DNN discriminant in the jet-process categories with 4 jets-$ \mathrm{ t \bar{t} } + \text{lf} $. The error bands include the total uncertainty after the fit to data. The distribution observed in data (markers) is overlayed. |
png pdf |
Figure 6-d:
Final discriminant shape in the single-lepton (SL) channel after the fit to data: DNN discriminant in the jet-process categories with $\geq $6 jets-$ \mathrm{ t \bar{t} } + \mathrm{ c \bar{c} } $. The error bands include the total uncertainty after the fit to data. The distribution observed in data (markers) is overlayed. |
png pdf |
Figure 7:
Final discriminant shapes in the dilepton (DL) channel after the fit to data: BDT discriminant in the analysis category with ($\geq$4 jets, 3 b-tags) (top row) and MEM discriminant in the analysis categories with ($\geq$4 jets, $\geq$4 b-tags) (bottom row) with low (left) and high (right) BDT output. The error bands include the total uncertainty after the fit to data. The distributions observed in data (markers) are overlayed. |
png pdf |
Figure 7-a:
Final discriminant shapes in the dilepton (DL) channel after the fit to data: BDT discriminant in the analysis category with ($\geq$4 jets, 3 b-tags). The error bands include the total uncertainty after the fit to data. The distribution observed in data (markers) is overlayed. |
png pdf |
Figure 7-b:
Final discriminant shapes in the dilepton (DL) channel after the fit to data: MEM discriminant in the analysis category with ($\geq$4 jets, $\geq$4 b-tags) with low BDT output. The error bands include the total uncertainty after the fit to data. The distribution observed in data (markers) is overlayed. |
png pdf |
Figure 7-c:
Final discriminant shapes in the dilepton (DL) channel after the fit to data: MEM discriminant in the analysis category with ($\geq$4 jets, $\geq$4 b-tags) with high BDT output. The error bands include the total uncertainty after the fit to data. The distribution observed in data (markers) is overlayed. |
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Figure 8:
Bins of the final discriminants as used in the fit (left), re-ordered by the pre-fit expected signal-to-background ratio (S/B). Each of the shown bins includes multiple bins of the final discriminants with similar S/B. The background is shown post-fit (S+B), with the fitted signal in cyan compared to the expectation for the SM Higgs boson ($\mu =$ 1) in red. Best-fit values of the signal strength modifiers $\mu $ (right) with their $ \pm $1$ \sigma $ confidence intervals (outer error bar), also split into their statistical (inner error bar) and systematic components. |
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Figure 8-a:
Bins of the final discriminants as used in the fit, re-ordered by the pre-fit expected signal-to-background ratio (S/B). Each of the shown bins includes multiple bins of the final discriminants with similar S/B. The background is shown post-fit (S+B), with the fitted signal in cyan compared to the expectation for the SM Higgs boson ($\mu =$ 1) in red. |
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Figure 8-b:
Best-fit values of the signal strength modifiers $\mu $ with their $ \pm $1$ \sigma $ confidence intervals (outer error bar), also split into their statistical (inner error bar) and systematic components. |
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Figure 9:
Median expected (dashed line) and observed (markers) 95% CL upper limits on $\mu $. The expected limits are displayed together with $ \pm $1$ \sigma $ and $ \pm $2$ \sigma $ confidence intervals (green and yellow bands). Also shown is the observed limit that is expected in case a SM $ \mathrm{ t\bar{t} H } $ signal ($\mu =1$) is present in the data (solid red line). |
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Figure 10:
Final discriminant (DNN) shapes in the single-lepton channel before the fit to data, in the ''jet-process'' categories with (4 jets, 3 b-tags) and (from top left to bottom right) $ \mathrm{ t\bar{t} H } $, $ \mathrm{ t \bar{t} } + \mathrm{ b \bar{b} } $, $ \mathrm{ t \bar{t} } + \text{2b} $, $ \mathrm{ t \bar{t} } + \text{b} $, $ \mathrm{ t \bar{t} } + \mathrm{ c \bar{c} } $ and $ \mathrm{ t \bar{t} } + \text{lf} $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. |
png pdf |
Figure 10-a:
Final discriminant (DNN) shape in the single-lepton channel before the fit to data, in the ''jet-process'' categories with (4 jets, 3 b-tags) and $ \mathrm{ t\bar{t} H } $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. |
png pdf |
Figure 10-b:
Final discriminant (DNN) shape in the single-lepton channel before the fit to data, in the ''jet-process'' categories with (4 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \mathrm{ b \bar{b} } $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. |
png pdf |
Figure 10-c:
Final discriminant (DNN) shape in the single-lepton channel before the fit to data, in the ''jet-process'' categories with (4 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \text{2b} $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. |
png pdf |
Figure 10-d:
Final discriminant (DNN) shape in the single-lepton channel before the fit to data, in the ''jet-process'' categories with (4 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \text{b} $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. |
png pdf |
Figure 10-e:
Final discriminant (DNN) shape in the single-lepton channel before the fit to data, in the ''jet-process'' categories with (4 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \mathrm{ c \bar{c} } $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. |
png pdf |
Figure 10-f:
Final discriminant (DNN) shape in the single-lepton channel before the fit to data, in the ''jet-process'' categories with (4 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \text{lf} $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. |
png pdf |
Figure 11:
Final discriminant (DNN) shapes in the single-lepton channel before the fit to data, in the ''jet-process'' categories with (5 jets, 3 b-tags) and (from top left to bottom right) $ \mathrm{ t\bar{t} H } $, $ \mathrm{ t \bar{t} } + \mathrm{ b \bar{b} } $, $ \mathrm{ t \bar{t} } + \text{2b} $, $ \mathrm{ t \bar{t} } + \text{b} $, $ \mathrm{ t \bar{t} } + \mathrm{ c \bar{c} } $ and $ \mathrm{ t \bar{t} } + \text{lf} $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. |
png pdf |
Figure 11-a:
Final discriminant (DNN) shape in the single-lepton channel before the fit to data, in the ''jet-process'' categories with (5 jets, 3 b-tags) and $ \mathrm{ t\bar{t} H } $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. |
png pdf |
Figure 11-b:
Final discriminant (DNN) shape in the single-lepton channel before the fit to data, in the ''jet-process'' categories with (5 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \mathrm{ b \bar{b} } $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. |
png pdf |
Figure 11-c:
Final discriminant (DNN) shape in the single-lepton channel before the fit to data, in the ''jet-process'' categories with (5 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \text{2b} $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. |
png pdf |
Figure 11-d:
Final discriminant (DNN) shape in the single-lepton channel before the fit to data, in the ''jet-process'' categories with (5 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \text{b} $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. |
png pdf |
Figure 11-e:
Final discriminant (DNN) shape in the single-lepton channel before the fit to data, in the ''jet-process'' categories with (5 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \mathrm{ c \bar{c} } $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. |
png pdf |
Figure 11-f:
Final discriminant (DNN) shape in the single-lepton channel before the fit to data, in the ''jet-process'' categories with (5 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \text{lf} $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. |
png pdf |
Figure 12:
Final discriminant (DNN) shapes in the single-lepton channel before the fit to data, in the ''jet-process'' categories with ($\geq$6 jets, 3 b-tags) and (from top left to bottom right) $ \mathrm{ t\bar{t} H } $, $ \mathrm{ t \bar{t} } + \mathrm{ b \bar{b} } $, $ \mathrm{ t \bar{t} } + \text{2b} $, $ \mathrm{ t \bar{t} } + \text{b} $, $ \mathrm{ t \bar{t} } + \mathrm{ c \bar{c} } $ and $ \mathrm{ t \bar{t} } + \text{lf} $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. |
png pdf |
Figure 12-a:
Final discriminant (DNN) shape in the single-lepton channel before the fit to data, in the ''jet-process'' categories with ($\geq$6 jets, 3 b-tags) and $ \mathrm{ t\bar{t} H } $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. |
png pdf |
Figure 12-b:
Final discriminant (DNN) shape in the single-lepton channel before the fit to data, in the ''jet-process'' categories with ($\geq$6 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \mathrm{ b \bar{b} } $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. |
png pdf |
Figure 12-c:
Final discriminant (DNN) shape in the single-lepton channel before the fit to data, in the ''jet-process'' categories with ($\geq$6 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \text{2b} $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. |
png pdf |
Figure 12-d:
Final discriminant (DNN) shape in the single-lepton channel before the fit to data, in the ''jet-process'' categories with ($\geq$6 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \text{b} $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. |
png pdf |
Figure 12-e:
Final discriminant (DNN) shape in the single-lepton channel before the fit to data, in the ''jet-process'' categories with ($\geq$6 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \mathrm{ c \bar{c} } $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. |
png pdf |
Figure 12-f:
Final discriminant (DNN) shape in the single-lepton channel before the fit to data, in the ''jet-process'' categories with ($\geq$6 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \text{lf} $. The expected background contributions (filled histograms) are stacked, and the expected signal distribution (line) for a Higgs-boson mass of $ {m_{\mathrm{H}}} = $ 125 GeV is superimposed. Each contribution is normalized to an integrated luminosity of 35.9 fb$^{-1}$, and the signal distribution is additionally scaled by a factor of 15 for better readability. The error bands include the total uncertainty of the fit model. |
png pdf |
Figure 13:
Final discriminant (DNN) shapes in the single-lepton channel after the fit to data, in the ''jet-process'' categories with (4 jets, 3 b-tags) and (from top left to bottom right) $ \mathrm{ t\bar{t} H } $, $ \mathrm{ t \bar{t} } + \mathrm{ b \bar{b} } $, $ \mathrm{ t \bar{t} } + \text{2b} $, $ \mathrm{ t \bar{t} } + \text{b} $, $ \mathrm{ t \bar{t} } + \mathrm{ c \bar{c} } $ and $ \mathrm{ t \bar{t} } + \text{lf} $. The error bands include the total uncertainty after the fit to data. |
png pdf |
Figure 13-a:
Final discriminant (DNN) shape in the single-lepton channel after the fit to data, in the ''jet-process'' categories with (4 jets, 3 b-tags) and $ \mathrm{ t\bar{t} H } $. The error bands include the total uncertainty after the fit to data. |
png pdf |
Figure 13-b:
Final discriminant (DNN) shape in the single-lepton channel after the fit to data, in the ''jet-process'' categories with (4 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \mathrm{ b \bar{b} } $. The error bands include the total uncertainty after the fit to data. |
png pdf |
Figure 13-c:
Final discriminant (DNN) shape in the single-lepton channel after the fit to data, in the ''jet-process'' categories with (4 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \text{2b} $. The error bands include the total uncertainty after the fit to data. |
png pdf |
Figure 13-d:
Final discriminant (DNN) shape in the single-lepton channel after the fit to data, in the ''jet-process'' categories with (4 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \text{b} $. The error bands include the total uncertainty after the fit to data. |
png pdf |
Figure 13-e:
Final discriminant (DNN) shape in the single-lepton channel after the fit to data, in the ''jet-process'' categories with (4 jets, 3 b-tags) and \mathrm{ t \bar{t} } + \mathrm{ c \bar{c} } $. The error bands include the total uncertainty after the fit to data. |
png pdf |
Figure 13-f:
Final discriminant (DNN) shape in the single-lepton channel after the fit to data, in the ''jet-process'' categories with (4 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \text{lf} $. The error bands include the total uncertainty after the fit to data. |
png pdf |
Figure 14:
Final discriminant (DNN) shapes in the single-lepton channel after the fit to data, in the ''jet-process'' categories with (5 jets, 3 b-tags) and (from top left to bottom right) $ \mathrm{ t\bar{t} H } $, $ \mathrm{ t \bar{t} } + \mathrm{ b \bar{b} } $, $ \mathrm{ t \bar{t} } + \text{2b} $, $ \mathrm{ t \bar{t} } + \text{b} $, $ \mathrm{ t \bar{t} } + \mathrm{ c \bar{c} } $ and $ \mathrm{ t \bar{t} } + \text{lf} $. The error bands include the total uncertainty after the fit to data. |
png pdf |
Figure 14-a:
Final discriminant (DNN) shape in the single-lepton channel after the fit to data, in the ''jet-process'' categories with (5 jets, 3 b-tags) and $ \mathrm{ t\bar{t} H } $. The error bands include the total uncertainty after the fit to data. |
png pdf |
Figure 14-b:
Final discriminant (DNN) shape in the single-lepton channel after the fit to data, in the ''jet-process'' categories with (5 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \mathrm{ b \bar{b} } $. The error bands include the total uncertainty after the fit to data. |
png pdf |
Figure 14-c:
Final discriminant (DNN) shape in the single-lepton channel after the fit to data, in the ''jet-process'' categories with (5 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \text{2b} $. The error bands include the total uncertainty after the fit to data. |
png pdf |
Figure 14-d:
Final discriminant (DNN) shape in the single-lepton channel after the fit to data, in the ''jet-process'' categories with (5 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \text{b} $. The error bands include the total uncertainty after the fit to data. |
png pdf |
Figure 14-e:
Final discriminant (DNN) shape in the single-lepton channel after the fit to data, in the ''jet-process'' categories with (5 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \mathrm{ c \bar{c} } $. The error bands include the total uncertainty after the fit to data. |
png pdf |
Figure 14-f:
Final discriminant (DNN) shape in the single-lepton channel after the fit to data, in the ''jet-process'' categories with (5 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \text{lf} $. The error bands include the total uncertainty after the fit to data. |
png pdf |
Figure 15:
Final discriminant (DNN) shapes in the single-lepton channel after the fit to data, in the ''jet-process'' categories with ($\geq$6 jets, 3 b-tags) and (from top left to bottom right) $ \mathrm{ t\bar{t} H } $, $ \mathrm{ t \bar{t} } + \mathrm{ b \bar{b} } $, $ \mathrm{ t \bar{t} } + \text{2b} $, $ \mathrm{ t \bar{t} } + \text{b} $, $ \mathrm{ t \bar{t} } + \mathrm{ c \bar{c} } $ and $ \mathrm{ t \bar{t} } + \text{lf} $. The error bands include the total uncertainty after the fit to data. |
png pdf |
Figure 15-a:
Final discriminant (DNN) shape in the single-lepton channel after the fit to data, in the ''jet-process'' categories with ($\geq$6 jets, 3 b-tags) and $ \mathrm{ t\bar{t} H } $. The error bands include the total uncertainty after the fit to data. |
png pdf |
Figure 15-b:
Final discriminant (DNN) shape in the single-lepton channel after the fit to data, in the ''jet-process'' categories with ($\geq$6 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \mathrm{ b \bar{b} } $. The error bands include the total uncertainty after the fit to data. |
png pdf |
Figure 15-c:
Final discriminant (DNN) shape in the single-lepton channel after the fit to data, in the ''jet-process'' categories with ($\geq$6 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \text{2b} $. The error bands include the total uncertainty after the fit to data. |
png pdf |
Figure 15-d:
Final discriminant (DNN) shape in the single-lepton channel after the fit to data, in the ''jet-process'' categories with ($\geq$6 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \text{b} $. The error bands include the total uncertainty after the fit to data. |
png pdf |
Figure 15-e:
Final discriminant (DNN) shape in the single-lepton channel after the fit to data, in the ''jet-process'' categories with ($\geq$6 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \mathrm{ c \bar{c} } $. The error bands include the total uncertainty after the fit to data. |
png pdf |
Figure 15-f:
Final discriminant (DNN) shape in the single-lepton channel after the fit to data, in the ''jet-process'' categories with ($\geq$6 jets, 3 b-tags) and $ \mathrm{ t \bar{t} } + \text{lf} $. The error bands include the total uncertainty after the fit to data. |
| Tables | |
png pdf |
Table 1:
Event yields observed in data and predicted by the simulation after the baseline selection requirements in the single-lepton (SL) channel (at least four jets, at least two of which are b tagged) and dilepton (DL) channel (at least three jets, at least one of which is b tagged). The quoted uncertainties are statistical only. |
png pdf |
Table 2:
Systematic uncertainties considered in the analysis. |
png pdf |
Table 3:
Observed and expected event yields per jet-process category in the single-lepton channel with 4 jets and at least 3 b-tags, prior to the fit to data (after the fit to data). The quoted uncertainties denote the total statistical and systematic uncertainty. |
png pdf |
Table 4:
Observed and expected event yields per jet-process category in the single-lepton channel with 5 jets and at least 3 b-tags, prior to the fit to data (after the fit to data). The quoted uncertainties denote the total statistical and systematic uncertainty. |
png pdf |
Table 5:
Observed and expected event yields per jet-process category in the single-lepton channel with at least 6 jets and at least 3 b-tags, prior to the fit to data (after the fit to data). The quoted uncertainties denote the total statistical and systematic uncertainty. |
png pdf |
Table 6:
Observed and expected event yields per jet-tag category in the dilepton channel, prior to the fit to data (after the fit to data). The quoted uncertainties denote the total statistical and systematic uncertainty. |
png pdf |
Table 7:
Best-fit value of the signal strength modifier $\mu $ and the observed and median expected 95% CL upper limits in the dilepton and the single-lepton channels as well as the combined results. The one standard deviation ( $ \pm $1$ \sigma $) confidence intervals of the expected limit and the best-fit value are also quoted, split into the statistical and systematic components in the latter case. Expected limits are calculated with the asymptotic method [83]. |
png pdf |
Table 8:
Contributions of different sources of uncertainties to the result for the fit to the data (observed) and to the expectation from simulation (expected). The quoted uncertainties $\sigma _{\mu}$ on $\mu $ are obtained by fixing the listed uncertainties in the fit, and subtracting the obtained result in quadrature from the result of the full fit. The quadratic sum of the contributions is different from the total uncertainty due to correlations between the nuisance parameters. |
| Summary |
| A search for the associated production of a Higgs boson and a top quark-antiquark pair is performed using 35.9 fb$^{-1}$ value of pp collision data recorded with the CMS detector at a center-of-mass energy of 13 TeV in 2016. Candidate events are selected in final states compatible with the Higgs boson decay $ \text{H} \rightarrow \text{bb} $ and the single-lepton and dilepton decay channels of the $\mathrm{t\bar{t}} $ pair. Selected events are split into mutually exclusive categories according to their $\mathrm{t\bar{t}}$ decay channel and jet content. In each category a powerful discriminant is constructed to separate the $ \mathrm{ t\bar{t} H } $ signal from the $ \mathrm{t\bar{t}} $-dominated background, based on different multivariate analysis techniques (boosted decision trees, matrix element method, deep neural networks). An observed (expected) upper limit on the $ \mathrm{ t\bar{t} H } $ production cross section relative to the SM expectations of $\mu = $ 1.5 (0.9) at the 95% confidence level is obtained. The best-fit value of $\mu$ is 0.72 $\pm$ 0.24 (stat) $\pm$ 0.38 (syst). These results correspond to a significance of 1.6 standard deviations above the background-only hypothesis. |
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