CMS-HIG-18-009 ; CERN-EP-2018-305 | ||
Search for associated production of a Higgs boson and a single top quark in proton-proton collisions at $\sqrt{s} = $ 13 TeV | ||
CMS Collaboration | ||
23 November 2018 | ||
Phys. Rev. D 99 (2019) 092005 | ||
Abstract: A search is presented for the production of a Higgs boson in association with a single top quark, based on data collected in 2016 by the CMS experiment at the LHC at a center-of-mass energy of 13 TeV, which corresponds to an integrated luminosity of 35.9 fb$^{-1}$ . The production cross section for this process is highly sensitive to the absolute values of the top quark Yukawa coupling, ${y_\mathrm{t}} $, the Higgs boson coupling to vector bosons, ${g_{\mathrm{H}\mathrm{VV}}} $, and, uniquely, to their relative sign. Analyses using multilepton signatures, targeting $\mathrm{H}\to\mathrm{W}\mathrm{W}$, $\mathrm{H}\to\tau\tau$, and $\mathrm{H}\to\mathrm{Z}\mathrm{Z}$ decay modes, and signatures with a single lepton and a $\mathrm{b\bar{b}}$ pair, targeting the $\mathrm{H}\to\mathrm{b\bar{b}}$ decay, are combined with a reinterpretation of a measurement in the $\mathrm{H}\to{\gamma\gamma} $ channel to constrain ${y_\mathrm{t}} $. For a standard model-like value of ${g_{\mathrm{H}\mathrm{VV}}} $, the data favor positive values of ${y_\mathrm{t}} $ and exclude values of ${y_\mathrm{t}} $ below about $-0.9\,{y_\mathrm{t}} ^\mathrm{SM}$. | ||
Links: e-print arXiv:1811.09696 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; HepData record ; CADI line (restricted) ; |
Figures & Tables | Summary | Additional Figures | References | CMS Publications |
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Figures | |
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Figure 1:
Leading order Feynman diagrams for the associated production of a single top quark and a Higgs boson in the $t$ channel, where the Higgs boson couples either to the top quark (left) or the W boson (right). |
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Figure 1-a:
Leading order Feynman diagras for the associated production of a single top quark and a Higgs boson in the $t$ channel, where the Higgs boson couples to the top quark. |
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Figure 1-b:
Leading order Feynman diagras for the associated production of a single top quark and a Higgs boson in the $t$ channel, where the Higgs boson couples to the W boson. |
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Figure 2:
Distributions of discriminating observables for the same-sign $ {{{\mu}}^\pm {{\mu}}^\pm} $ channel, normalized to 35.9 fb$^{-1}$, before fitting the signal discriminant to the data. The grey band represents the unconstrained (pre-fit) statistical and systematic uncertainties. In the panel below each distribution, the ratio of the observed and predicted event yields is shown. The shape of the two $ {{\mathrm {t}} {\mathrm {H}}} $ signals for $ {\kappa _ {\mathrm {t}}} =-1.0$ is shown, normalized to their respective cross sections for $ {\kappa _ {\mathrm {t}}} =-1.0$, ${\kappa _\text {V}} =1.0$. |
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Figure 2-a:
Distribution of a discriminating observable for the same-sign $ {{{\mu}}^\pm {{\mu}}^\pm} $ channel, normalized to 35.9 fb$^{-1}$, before fitting the signal discriminant to the data. The grey band represents the unconstrained (pre-fit) statistical and systematic uncertainties. In the panel below the distribution, the ratio of the observed and predicted event yields is shown. The shape of the two $ {{\mathrm {t}} {\mathrm {H}}} $ signals for $ {\kappa _ {\mathrm {t}}} =-1.0$ is shown, normalized to their respective cross sections for $ {\kappa _ {\mathrm {t}}} =-1.0$, ${\kappa _\text {V}} =1.0$. |
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Figure 2-b:
Distribution of a discriminating observable for the same-sign $ {{{\mu}}^\pm {{\mu}}^\pm} $ channel, normalized to 35.9 fb$^{-1}$, before fitting the signal discriminant to the data. The grey band represents the unconstrained (pre-fit) statistical and systematic uncertainties. In the panel below the distribution, the ratio of the observed and predicted event yields is shown. The shape of the two $ {{\mathrm {t}} {\mathrm {H}}} $ signals for $ {\kappa _ {\mathrm {t}}} =-1.0$ is shown, normalized to their respective cross sections for $ {\kappa _ {\mathrm {t}}} =-1.0$, ${\kappa _\text {V}} =1.0$. |
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Figure 2-c:
Distribution of a discriminating observable for the same-sign $ {{{\mu}}^\pm {{\mu}}^\pm} $ channel, normalized to 35.9 fb$^{-1}$, before fitting the signal discriminant to the data. The grey band represents the unconstrained (pre-fit) statistical and systematic uncertainties. In the panel below the distribution, the ratio of the observed and predicted event yields is shown. The shape of the two $ {{\mathrm {t}} {\mathrm {H}}} $ signals for $ {\kappa _ {\mathrm {t}}} =-1.0$ is shown, normalized to their respective cross sections for $ {\kappa _ {\mathrm {t}}} =-1.0$, ${\kappa _\text {V}} =1.0$. |
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Figure 3:
Distributions of discriminating observables for the same-sign $ {{\mathrm {e}^\pm} {{\mu}}^\pm} $ channel, normalized to 35.9 fb$^{-1}$, before fitting the signal discriminant to the data. The grey band represents the unconstrained (pre-fit) statistical and systematic uncertainties. In the panel below each distribution, the ratio of the observed and predicted event yields is shown. The shape of the two $ {{\mathrm {t}} {\mathrm {H}}} $ signals for $ {\kappa _ {\mathrm {t}}} =-1.0$ is shown, normalized to their respective cross sections for $ {\kappa _ {\mathrm {t}}} =-1.0$, ${\kappa _\text {V}} =1.0$. |
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Figure 3-a:
Distribution of a discriminating observable for the same-sign $ {{\mathrm {e}^\pm} {{\mu}}^\pm} $ channel, normalized to 35.9 fb$^{-1}$, before fitting the signal discriminant to the data. The grey band represents the unconstrained (pre-fit) statistical and systematic uncertainties. In the panel below the distribution, the ratio of the observed and predicted event yields is shown. The shape of the two $ {{\mathrm {t}} {\mathrm {H}}} $ signals for $ {\kappa _ {\mathrm {t}}} =-1.0$ is shown, normalized to their respective cross sections for $ {\kappa _ {\mathrm {t}}} =-1.0$, ${\kappa _\text {V}} =1.0$. |
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Figure 3-b:
Distribution of a discriminating observable for the same-sign $ {{\mathrm {e}^\pm} {{\mu}}^\pm} $ channel, normalized to 35.9 fb$^{-1}$, before fitting the signal discriminant to the data. The grey band represents the unconstrained (pre-fit) statistical and systematic uncertainties. In the panel below the distribution, the ratio of the observed and predicted event yields is shown. The shape of the two $ {{\mathrm {t}} {\mathrm {H}}} $ signals for $ {\kappa _ {\mathrm {t}}} =-1.0$ is shown, normalized to their respective cross sections for $ {\kappa _ {\mathrm {t}}} =-1.0$, ${\kappa _\text {V}} =1.0$. |
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Figure 3-c:
Distribution of a discriminating observable for the same-sign $ {{\mathrm {e}^\pm} {{\mu}}^\pm} $ channel, normalized to 35.9 fb$^{-1}$, before fitting the signal discriminant to the data. The grey band represents the unconstrained (pre-fit) statistical and systematic uncertainties. In the panel below the distribution, the ratio of the observed and predicted event yields is shown. The shape of the two $ {{\mathrm {t}} {\mathrm {H}}} $ signals for $ {\kappa _ {\mathrm {t}}} =-1.0$ is shown, normalized to their respective cross sections for $ {\kappa _ {\mathrm {t}}} =-1.0$, ${\kappa _\text {V}} =1.0$. |
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Figure 4:
Distributions of discriminating observables for the three lepton channel, normalized to 35.9 fb$^{-1}$, before fitting the signal discriminant to the data. The grey band represents the unconstrained (pre-fit) statistical and systematic uncertainties. In the panel below each distribution, the ratio of the observed and predicted event yields is shown. The shape of the two $ {{\mathrm {t}} {\mathrm {H}}} $ signals for $ {\kappa _ {\mathrm {t}}} =-1.0$ is shown, normalized to their respective cross sections for $ {\kappa _ {\mathrm {t}}} =-1.0$, ${\kappa _\text {V}} =1.0$. |
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Figure 4-a:
Distribution of a discriminating observablea for the three lepton channel, normalized to 35.9 fb$^{-1}$, before fitting the signal discriminant to the data. The grey band represents the unconstrained (pre-fit) statistical and systematic uncertainties. In the panel below the distribution, the ratio of the observed and predicted event yields is shown. The shape of the two $ {{\mathrm {t}} {\mathrm {H}}} $ signals for $ {\kappa _ {\mathrm {t}}} =-1.0$ is shown, normalized to their respective cross sections for $ {\kappa _ {\mathrm {t}}} =-1.0$, ${\kappa _\text {V}} =1.0$. |
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Figure 4-b:
Distribution of a discriminating observablea for the three lepton channel, normalized to 35.9 fb$^{-1}$, before fitting the signal discriminant to the data. The grey band represents the unconstrained (pre-fit) statistical and systematic uncertainties. In the panel below the distribution, the ratio of the observed and predicted event yields is shown. The shape of the two $ {{\mathrm {t}} {\mathrm {H}}} $ signals for $ {\kappa _ {\mathrm {t}}} =-1.0$ is shown, normalized to their respective cross sections for $ {\kappa _ {\mathrm {t}}} =-1.0$, ${\kappa _\text {V}} =1.0$. |
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Figure 4-c:
Distribution of a discriminating observablea for the three lepton channel, normalized to 35.9 fb$^{-1}$, before fitting the signal discriminant to the data. The grey band represents the unconstrained (pre-fit) statistical and systematic uncertainties. In the panel below the distribution, the ratio of the observed and predicted event yields is shown. The shape of the two $ {{\mathrm {t}} {\mathrm {H}}} $ signals for $ {\kappa _ {\mathrm {t}}} =-1.0$ is shown, normalized to their respective cross sections for $ {\kappa _ {\mathrm {t}}} =-1.0$, ${\kappa _\text {V}} =1.0$. |
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Figure 5:
Pre-fit classifier outputs, for the $ {{{\mu}}^\pm {{\mu}}^\pm} $ channel (left), $ {{\mathrm {e}^\pm} {{\mu}}^\pm} $ channel (center), and three-lepton channel (right), for training against ${{{\mathrm {t}\overline {\mathrm {t}}}} \mathrm {V}} $ (top row) and against ${{{\mathrm {t}\overline {\mathrm {t}}}} {+}\text {jets}} $ (bottom row). In the box below each distribution, the ratio of the observed and predicted event yields is shown. The shape of the two $ {{\mathrm {t}} {\mathrm {H}}} $ signals for $ {\kappa _ {\mathrm {t}}} =-1.0$ is shown, normalized to their respective cross sections for $ {\kappa _ {\mathrm {t}}} =-1.0$, ${\kappa _\text {V}} =1.0$. The grey band represents the unconstrained (pre-fit) statistical and systematic uncertainties. |
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Figure 5-a:
Pre-fit classifier output, for the $ {{{\mu}}^\pm {{\mu}}^\pm} $ channel, for training against ${{{\mathrm {t}\overline {\mathrm {t}}}} \mathrm {V}} $. In the box below the distribution, the ratio of the observed and predicted event yields is shown. The shape of the two $ {{\mathrm {t}} {\mathrm {H}}} $ signals for $ {\kappa _ {\mathrm {t}}} =-1.0$ is shown, normalized to their respective cross sections for $ {\kappa _ {\mathrm {t}}} =-1.0$, ${\kappa _\text {V}} =1.0$. The grey band represents the unconstrained (pre-fit) statistical and systematic uncertainties. |
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Figure 5-b:
Pre-fit classifier output, for the $ {{\mathrm {e}^\pm} {{\mu}}^\pm} $ channel, for training against ${{{\mathrm {t}\overline {\mathrm {t}}}} \mathrm {V}} $. In the box below the distribution, the ratio of the observed and predicted event yields is shown. The shape of the two $ {{\mathrm {t}} {\mathrm {H}}} $ signals for $ {\kappa _ {\mathrm {t}}} =-1.0$ is shown, normalized to their respective cross sections for $ {\kappa _ {\mathrm {t}}} =-1.0$, ${\kappa _\text {V}} =1.0$. The grey band represents the unconstrained (pre-fit) statistical and systematic uncertainties. |
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Figure 5-c:
Pre-fit classifier output, for the three-lepton channel, for training against ${{{\mathrm {t}\overline {\mathrm {t}}}} \mathrm {V}} $. In the box below the distribution, the ratio of the observed and predicted event yields is shown. The shape of the two $ {{\mathrm {t}} {\mathrm {H}}} $ signals for $ {\kappa _ {\mathrm {t}}} =-1.0$ is shown, normalized to their respective cross sections for $ {\kappa _ {\mathrm {t}}} =-1.0$, ${\kappa _\text {V}} =1.0$. The grey band represents the unconstrained (pre-fit) statistical and systematic uncertainties. |
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Figure 5-d:
Pre-fit classifier output, for the $ {{{\mu}}^\pm {{\mu}}^\pm} $ channel, for training against ${{{\mathrm {t}\overline {\mathrm {t}}}} {+}\text {jets}} $. In the box below the distribution, the ratio of the observed and predicted event yields is shown. The shape of the two $ {{\mathrm {t}} {\mathrm {H}}} $ signals for $ {\kappa _ {\mathrm {t}}} =-1.0$ is shown, normalized to their respective cross sections for $ {\kappa _ {\mathrm {t}}} =-1.0$, ${\kappa _\text {V}} =1.0$. The grey band represents the unconstrained (pre-fit) statistical and systematic uncertainties. |
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Figure 5-e:
Pre-fit classifier output, for the $ {{\mathrm {e}^\pm} {{\mu}}^\pm} $ channel, for training against ${{{\mathrm {t}\overline {\mathrm {t}}}} {+}\text {jets}} $. In the box below the distribution, the ratio of the observed and predicted event yields is shown. The shape of the two $ {{\mathrm {t}} {\mathrm {H}}} $ signals for $ {\kappa _ {\mathrm {t}}} =-1.0$ is shown, normalized to their respective cross sections for $ {\kappa _ {\mathrm {t}}} =-1.0$, ${\kappa _\text {V}} =1.0$. The grey band represents the unconstrained (pre-fit) statistical and systematic uncertainties. |
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Figure 5-f:
Pre-fit classifier output, for the three-lepton channel, for training against ${{{\mathrm {t}\overline {\mathrm {t}}}} {+}\text {jets}} $. In the box below the distribution, the ratio of the observed and predicted event yields is shown. The shape of the two $ {{\mathrm {t}} {\mathrm {H}}} $ signals for $ {\kappa _ {\mathrm {t}}} =-1.0$ is shown, normalized to their respective cross sections for $ {\kappa _ {\mathrm {t}}} =-1.0$, ${\kappa _\text {V}} =1.0$. The grey band represents the unconstrained (pre-fit) statistical and systematic uncertainties. |
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Figure 6:
Post-fit categorized classifier outputs as used in the maximum likelihood fit for the $ {{{\mu}}^\pm {{\mu}}^\pm} $ channel (left), $ {{\mathrm {e}^\pm} {{\mu}}^\pm} $ channel (center), and three-lepton channel (right), for 35.9 fb$^{-1}$. In the box below each distribution, the ratio of the observed and predicted event yields is shown. The shape of the $ {{\mathrm {t}} {\mathrm {H}}} $ signal is indicated with 10 times the SM. |
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Figure 6-a:
Post-fit categorized classifier output as used in the maximum likelihood fit for the $ {{{\mu}}^\pm {{\mu}}^\pm} $ channel, for 35.9 fb$^{-1}$. In the box below the distribution, the ratio of the observed and predicted event yields is shown. The shape of the $ {{\mathrm {t}} {\mathrm {H}}} $ signal is indicated with 10 times the SM. |
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Figure 6-b:
Post-fit categorized classifier output as used in the maximum likelihood fit for the $ {{\mathrm {e}^\pm} {{\mu}}^\pm} $ channel, for 35.9 fb$^{-1}$. In the box below the distribution, the ratio of the observed and predicted event yields is shown. The shape of the $ {{\mathrm {t}} {\mathrm {H}}} $ signal is indicated with 10 times the SM. |
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Figure 6-c:
Post-fit categorized classifier output as used in the maximum likelihood fit for the three-lepton channel, for 35.9 fb$^{-1}$. In the box below the distribution, the ratio of the observed and predicted event yields is shown. The shape of the $ {{\mathrm {t}} {\mathrm {H}}} $ signal is indicated with 10 times the SM. |
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Figure 7:
Output values of the SC-BDT. |
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Figure 8:
Response values of the FC-BDT. The background consists of ${{{\mathrm {t}\overline {\mathrm {t}}}} {+} {{\mathrm {b}} {\overline {\mathrm {b}}}}}$, $ {{\mathrm {t}\overline {\mathrm {t}}}} +\mathrm {1\bar{b}}$, and $ {{\mathrm {t}\overline {\mathrm {t}}}} +\mathrm {2\bar{b}}$ events. |
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Figure 9:
Pre-fit classifier outputs of the signal classification BDT for the 3 tag channel (left) and the 4 tag channel (right), for 35.9 fb$^{-1}$. In the box below each distribution, the ratio of the observed and predicted event yields is shown. The shape of the $ {{\mathrm {t}} {\mathrm {H}}} $ signal is indicated with 800 times the SM. |
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Figure 9-a:
Pre-fit classifier output of the signal classification BDT for the 3 tag channel, for 35.9 fb$^{-1}$. In the box below the distribution, the ratio of the observed and predicted event yields is shown. The shape of the $ {{\mathrm {t}} {\mathrm {H}}} $ signal is indicated with 800 times the SM. |
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Figure 9-b:
Pre-fit classifier output of the signal classification BDT for the 4 tag channel, for 35.9 fb$^{-1}$. In the box below the distribution, the ratio of the observed and predicted event yields is shown. The shape of the $ {{\mathrm {t}} {\mathrm {H}}} $ signal is indicated with 800 times the SM. |
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Figure 10:
Post-fit classifier outputs of the signal classification BDT as used in the maximum likelihood fit for the 3 tag channel (left) and the 4 tag channel (right). In the box below each distribution, the ratio of the observed and predicted event yields is shown. The shape of the $ {{\mathrm {t}} {\mathrm {H}}} $ signal is indicated with 800 times the SM. |
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Figure 10-a:
Post-fit classifier output of the signal classification BDT as used in the maximum likelihood fit for the 3 tag channel. In the box below the distribution, the ratio of the observed and predicted event yields is shown. The shape of the $ {{\mathrm {t}} {\mathrm {H}}} $ signal is indicated with 800 times the SM. |
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Figure 10-b:
Post-fit classifier output of the signal classification BDT as used in the maximum likelihood fit for the 4 tag channel. In the box below the distribution, the ratio of the observed and predicted event yields is shown. The shape of the $ {{\mathrm {t}} {\mathrm {H}}} $ signal is indicated with 800 times the SM. |
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Figure 11:
Pre- (left) and post-fit (right) classifier outputs of the flavor classification BDT for the dilepton selection. In the box below each distribution, the ratio of the observed and predicted event yields is shown. |
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Figure 11-a:
Pre-fit classifier output of the flavor classification BDT for the dilepton selection. In the box below the distribution, the ratio of the observed and predicted event yields is shown. |
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Figure 11-b:
Post-fit classifier output of the flavor classification BDT for the dilepton selection. In the box below the distribution, the ratio of the observed and predicted event yields is shown. |
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Figure 12:
Acceptance and selection efficiency for the $ {{\mathrm {t}} {\mathrm {H}} {\mathrm {q}}} $ (red) and ${{\mathrm {t}} {\mathrm {H}} {\mathrm {W}}} $ (blue) signal processes as a function of $ {\kappa _ {\mathrm {t}}} / {\kappa _\text {V}} $, for the ${{{\mathrm {t}\overline {\mathrm {t}}}} {\mathrm {H}}} $ leptonic (solid lines) and ${{{\mathrm {t}\overline {\mathrm {t}}}} {\mathrm {H}}}$ hadronic categories (dashed lines) of the $ {\mathrm {H}} \to {\gamma \gamma} $ measurement. |
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Figure 13:
Scan of $-2\Delta \ln{(\mathcal {L})}$ versus ${\kappa _ {\mathrm {t}}}$ for the data (black line) and the individual channels (blue, red, and green), compared to Asimov data sets corresponding to the SM expectations (dashed lines). |
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Figure 14:
Observed and expected 95% CL upper limit on the $ {{\mathrm {t}} {\mathrm {H}}} $ cross section times combined $ {\mathrm {H}} \to {\mathrm {W}} {\mathrm {W}}^*+ {{\tau} {\tau}} + {\mathrm {Z}} {\mathrm {Z}} ^*+ {{\mathrm {b}} {\overline {\mathrm {b}}}} + {\gamma \gamma} $ branching fraction for different values of the coupling ratio ${\kappa _ {\mathrm {t}}}$. The expected limit is calculated on a background-only data set, i.e., without $ {{\mathrm {t}} {\mathrm {H}}} $ contribution, but including a ${\kappa _ {\mathrm {t}}} $-dependent contribution from ${{{\mathrm {t}\overline {\mathrm {t}}}} {\mathrm {H}}}$. The ${{{\mathrm {t}\overline {\mathrm {t}}}} {\mathrm {H}}} $ normalization is kept fixed in the fit, while the $ {{\mathrm {t}} {\mathrm {H}}} $ signal strength is allowed to float. |
Tables | |
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Table 1:
Summary of the event selection for the multilepton channels. |
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Table 2:
Data yields and expected backgrounds after the event selection for the three multilepton search channels in 35.9 fb$^{-1}$of integrated luminosity. Quoted uncertainties include statistical uncertainties reflecting the limited size of MC samples and data sidebands, and unconstrained systematic uncertainties. |
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Table 3:
Input observables to the signal discrimination classifier. |
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Table 4:
Summary of event selection for the single-lepton + $ {{\mathrm {b}} {\overline {\mathrm {b}}}} $ channels. |
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Table 5:
Subcategories of ${{{\mathrm {t}\overline {\mathrm {t}}}} {+}\text {jets}} $ backgrounds used in the analysis. |
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Table 6:
Data yields and expected backgrounds after the event selection for the two signal regions and in the dilepton control region. Uncertainties include both systematic and statistical components. |
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Table 7:
Classification variable description |
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Table 8:
Input variables used in the training of the FC-BDT. The variables are sorted by their importance in the training within each category. In total, eight variables are used for the training of the FC-BDT. |
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Table 9:
Summary of the main sources of systematic uncertainty. $\Delta \mu /\mu $ corresponds to the relative change in ${{\mathrm {t}} {\mathrm {H}} + {{{\mathrm {t}\overline {\mathrm {t}}}} {\mathrm {H}}}} $ signal yield induced by varying the systematic source within its associated uncertainty. |
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Table 10:
Expected and observed 95% CL upper limits on the $ {{\mathrm {t}} {\mathrm {H}}} $ production cross section times $ {\mathrm {H}} \to {\mathrm {W}} {\mathrm {W}}^*+ {{\tau} {\tau}} + {\mathrm {Z}} {\mathrm {Z}} ^*+ {{\mathrm {b}} {\overline {\mathrm {b}}}} + {\gamma \gamma} $ branching fraction for a scenario of inverted couplings ($ {\kappa _ {\mathrm {t}}} =-1.0$, top rows) and for an SM-like signal ($ {\kappa _ {\mathrm {t}}} =1.0$, bottom rows), in pb. The expected limit is calculated on a background-only data set, i.e., without $ {{\mathrm {t}} {\mathrm {H}}} $ contribution, but including a ${\kappa _ {\mathrm {t}}} $-dependent contribution from the ${{{\mathrm {t}\overline {\mathrm {t}}}} {\mathrm {H}}}$ production. The ${{{\mathrm {t}\overline {\mathrm {t}}}} {\mathrm {H}}} $ normalization is kept fixed in the fit, while the $ {{\mathrm {t}} {\mathrm {H}}} $ signal strength is allowed to float. Limits can be compared to the expected product of $ {{\mathrm {t}} {\mathrm {H}}} $ cross sections and branching fractions of 0.83 and 0.077 pb for the inverted top quark Yukawa coupling and for the SM, respectively. |
Summary |
Events from proton-proton collisions at $\sqrt{s} = $ 13 TeV compatible with the production of a Higgs boson (H) in association with a single top quark (t) have been studied to derive constraints on the magnitude and relative sign of Higgs boson couplings to top quarks and vector bosons. Dedicated analyses of multilepton final states and final states with single leptons and a pair of bottom quarks are combined with a reinterpretation of a measurement of Higgs bosons decaying to two photons for the final result. For standard model-like Higgs boson couplings to vector bosons, the data favor a positive value of the top quark Yukawa coupling, ${y_\mathrm{t}} $, by about 1.5 standard deviations and exclude values outside the ranges of about $[-0.9, -0.5]$ and $[1.0, 2.1]$ times ${y_\mathrm{t}} ^\mathrm{SM}$ at the 95% confidence level. An excess of events compared with the expected backgrounds is compatible with the standard model expectation of ${\mathrm{t}\mathrm{H}+{\mathrm{t\bar{t}}\mathrm{H}} } $ production. |
Additional Figures | |
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Additional Figure 1:
List of most important nuisance parameters, ordered by their impact on a fit with a common ${{\mathrm {t}} {\mathrm {H}} + {{{\mathrm {t}\overline {\mathrm {t}}}} {\mathrm {H}}}} $ signal strength floating. The impact is defined as the shift in best-fit signal strength when fixing each nuisance to its post-fit value plus or minus one standard deviation. Also shown is the pull for each nuisance parameter, defined as post-fit minus pre-fit values divided by the pre-fit uncertainties, with the post-fit uncertainty indicated. |
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Additional Figure 2:
Scan of negative log-likelihood for a fit with two independently floating signal strengths for ${{\mathrm {t}} {\mathrm {H}}} $ ($\mu _ {{\mathrm {t}} {\mathrm {H}}} $) and ${{{\mathrm {t}\overline {\mathrm {t}}}} {\mathrm {H}}} $ ($\mu _ {{{\mathrm {t}\overline {\mathrm {t}}}} {\mathrm {H}}} $), for $ {\kappa _ {\mathrm {t}}} = $ 1.0 (SM). The best-fit value of $\mu _ {{\mathrm {t}} {\mathrm {H}}} = $ 9.63, $\mu _ {{{\mathrm {t}\overline {\mathrm {t}}}} {\mathrm {H}}} =$ 1.69 is indicated with a white cross. The SM expectation is indicated with a black cross and has a value of $-2\Delta \ln{\mathcal {L}}$ of 5.2, corresponding to a $p$-value of 7.6%, assuming it is distributed according to a $\chi ^2$ function with two degrees of freedom. |
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Additional Figure 3:
Production cross sections of ${{\mathrm {t}} {\mathrm {H}} {\mathrm {q}}} $ (red), ${{\mathrm {t}} {\mathrm {H}} {\mathrm {W}}} $ (blue), and ${{{\mathrm {t}\overline {\mathrm {t}}}} {\mathrm {H}}} $ (black) as a function of the ratio of coupling modifiers ${\kappa _ {\mathrm {t}}} $ and ${\kappa _\text {V}}$, for three different values of ${\kappa _\text {V}}$, for $\sqrt {s}= $ 13 TeV, see Refs. [17-19]. See also https://twiki.cern.ch/twiki/bin/view/LHCPhysics/LHCHXSWG2KAPPA. |
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