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| CMS-EXO-16-051 ; CERN-EP-2017-299 | ||
| Search for dark matter in events with energetic, hadronically decaying top quarks and missing transverse momentum at $\sqrt{s} = $ 13 TeV | ||
| CMS Collaboration | ||
| 25 January 2018 | ||
| JHEP 06 (2018) 027 | ||
| Abstract: A search for dark matter is conducted in events with large missing transverse momentum and a hadronically decaying, Lorentz-boosted top quark. This study is performed using proton-proton collisions at a center-of-mass energy of 13 TeV, in data recorded by the CMS detector in 2016 at the LHC, corresponding to an integrated luminosity of 36 fb$^{-1}$. New substructure techniques, including the novel use of energy correlation functions, are utilized to identify the decay products of the top quark. With no significant deviations observed from predictions of the standard model, limits are placed on the production of new heavy bosons coupling to dark matter particles. For a scenario with purely vector-like or purely axial-vector-like flavor changing neutral currents, mediator masses between 0.20 and 1.75 TeV are excluded at 95% confidence level, given a sufficiently small dark matter mass. Scalar resonances decaying into a top quark and a dark matter fermion are excluded for masses below 3.4 TeV, assuming a dark matter mass of 100 GeV. | ||
| Links: e-print arXiv:1801.08427 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; CADI line (restricted) ; | ||
| Figures | |
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Figure 1:
Example Feynman diagrams of monotop production via a flavor-changing neutral current V (left) and a charged, heavy scalar resonance $\phi $ (right). |
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Figure 1-a:
Example Feynman diagram of monotop production via a flavor-changing neutral current V. |
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Figure 1-b:
Example Feynman diagram of monotop production via a charged, heavy scalar resonance $\phi $. |
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Figure 2:
Performance of BDT tagging of top quark and q/g jets. The left figure shows the BDT output in both types of jets. The right figure shows the rate of misidentifying a q/g jet as a function of the efficiency of selecting top jets. In both figures, the $ {p_{\mathrm {T}}} $ spectra of jets are weighted to be uniform, and the $m_\mathrm {SD}$ is required to be in the range of 110-210 GeV. |
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Figure 2-a:
Performance of BDT tagging of top quark and q/g jets. The figure shows the BDT output in both types of jets. The $ {p_{\mathrm {T}}} $ spectra of jets are weighted to be uniform, and the $m_\mathrm {SD}$ is required to be in the range of 110-210 GeV. |
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Figure 2-b:
Performance of BDT tagging of top quark and q/g jets. The figure shows the rate of misidentifying a q/g jet as a function of the efficiency of selecting top jets. The $ {p_{\mathrm {T}}} $ spectra of jets are weighted to be uniform, and the $m_\mathrm {SD}$ is required to be in the range of 110-210 GeV. |
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Figure 3:
Comparison of the BDT response in data and in simulation, in samples enriched in top-quark jets (left) and q/g jets (right). The lower panel of each plot shows the ratio of the observed data to the SM prediction in each bin. The shaded bands represent the statistical uncertainties in the simulation. |
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Figure 3-a:
Comparison of the BDT response in data and in simulation, in samples enriched in top-quark jets. The lower panel shows the ratio of the observed data to the SM prediction in each bin. The shaded band represents the statistical uncertainties in the simulation. |
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Figure 3-b:
Comparison of the BDT response in data and in simulation, in samples enriched in q/g jets. The lower panel shows the ratio of the observed data to the SM prediction in each bin. The shaded band represents the statistical uncertainties in the simulation. |
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Figure 4:
Comparison between data and SM predictions in the dilepton control regions before and after performing the simultaneous fit to the different control regions and signal region. Each bin shows the event yields divided by the width of the bin. The upper row of figures corresponds to the dielectron control region, and the lower row to the dimuon control region. The left (right) column of figures corresponds to the loose (tight) category of the control regions. The blue solid line represents the sum of the SM contributions normalized to their fitted yields. The red dashed line represents the sum of the SM contributions normalized to the prediction. The stacked histograms show the individual fitted SM contributions. The lower panel of each figure shows the ratio of data to fitted prediction. The gray band on the ratio indicates the one standard deviation uncertainty on the prediction after propagating all the systematic uncertainties and their correlations in the fit. |
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Figure 4-a:
Comparison between data and SM predictions in the dilepton control regions before and after performing the simultaneous fit to the different control regions and signal region. Each bin shows the event yields divided by the width of the bin. The figure corresponds to the dielectron control region and the loose category of the control regions. The blue solid line represents the sum of the SM contributions normalized to their fitted yields. The red dashed line represents the sum of the SM contributions normalized to the prediction. The stacked histograms show the individual fitted SM contributions. The lower panel shows the ratio of data to fitted prediction. The gray band on the ratio indicates the one standard deviation uncertainty on the prediction after propagating all the systematic uncertainties and their correlations in the fit. |
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Figure 4-b:
Comparison between data and SM predictions in the dilepton control regions before and after performing the simultaneous fit to the different control regions and signal region. Each bin shows the event yields divided by the width of the bin. The figure corresponds to the dielectron control region and the tight category of the control regions. The blue solid line represents the sum of the SM contributions normalized to their fitted yields. The red dashed line represents the sum of the SM contributions normalized to the prediction. The stacked histograms show the individual fitted SM contributions. The lower panel shows the ratio of data to fitted prediction. The gray band on the ratio indicates the one standard deviation uncertainty on the prediction after propagating all the systematic uncertainties and their correlations in the fit. |
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Figure 4-c:
Comparison between data and SM predictions in the dilepton control regions before and after performing the simultaneous fit to the different control regions and signal region. Each bin shows the event yields divided by the width of the bin. The figure corresponds to the dimuon control region and the loose category of the control regions. The blue solid line represents the sum of the SM contributions normalized to their fitted yields. The red dashed line represents the sum of the SM contributions normalized to the prediction. The stacked histograms show the individual fitted SM contributions. The lower panel shows the ratio of data to fitted prediction. The gray band on the ratio indicates the one standard deviation uncertainty on the prediction after propagating all the systematic uncertainties and their correlations in the fit. |
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Figure 4-d:
Comparison between data and SM predictions in the dilepton control regions before and after performing the simultaneous fit to the different control regions and signal region. Each bin shows the event yields divided by the width of the bin. The figure corresponds to the dimuon control region and the tight category of the control regions. The blue solid line represents the sum of the SM contributions normalized to their fitted yields. The red dashed line represents the sum of the SM contributions normalized to the prediction. The stacked histograms show the individual fitted SM contributions. The lower panel shows the ratio of data to fitted prediction. The gray band on the ratio indicates the one standard deviation uncertainty on the prediction after propagating all the systematic uncertainties and their correlations in the fit. |
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Figure 5:
Comparison between data and SM predictions in the photon control regions before and after performing the simultaneous fit to the different control regions and signal region. Each bin shows the event yields divided by the width of the bin. The left (right) figure corresponds to the loose (tight) category of the control region. The blue solid line represents the sum of the SM contributions normalized to their fitted yields. The red dashed line represents the sum of the SM contributions normalized to the prediction. The stacked histograms show the individual fitted SM contributions. The lower panel of each figure shows the ratio of data to fitted prediction. The gray band on the ratio indicates the one standard deviation uncertainty on the prediction after propagating all the systematic uncertainties and their correlations in the fit. |
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Figure 5-a:
Comparison between data and SM predictions in the photon control regions before and after performing the simultaneous fit to the different control regions and signal region. Each bin shows the event yields divided by the width of the bin. The figure corresponds to the loose category of the control region. The blue solid line represents the sum of the SM contributions normalized to their fitted yields. The red dashed line represents the sum of the SM contributions normalized to the prediction. The stacked histograms show the individual fitted SM contributions. The lower panel shows the ratio of data to fitted prediction. The gray band on the ratio indicates the one standard deviation uncertainty on the prediction after propagating all the systematic uncertainties and their correlations in the fit. |
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Figure 5-b:
Comparison between data and SM predictions in the photon control regions before and after performing the simultaneous fit to the different control regions and signal region. Each bin shows the event yields divided by the width of the bin. The figure corresponds to the tight category of the control region. The blue solid line represents the sum of the SM contributions normalized to their fitted yields. The red dashed line represents the sum of the SM contributions normalized to the prediction. The stacked histograms show the individual fitted SM contributions. The lower panel shows the ratio of data to fitted prediction. The gray band on the ratio indicates the one standard deviation uncertainty on the prediction after propagating all the systematic uncertainties and their correlations in the fit. |
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Figure 6:
Comparison between data and SM predictions in the b-vetoed single lepton control regions before and after performing the simultaneous fit to the different control regions and signal region. Each bin shows the event yields divided by the width of the bin. The upper row of figures corresponds to the single electron b-vetoed control region, and lower row to the single muon b-vetoed control region. The left (right) column of figures corresponds to the loose (tight) category of the control regions. The blue solid line represents the sum of the SM contributions normalized to their fitted yields. The red dashed line represents the sum of the SM contributions normalized to the prediction. The stacked histograms show the individual fitted SM contributions. The lower panel of each figure shows the ratio of data to fitted prediction. The gray band on the ratio indicates the one standard deviation uncertainty on the prediction after propagating all the systematic uncertainties and their correlations in the fit. |
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Figure 6-a:
Comparison between data and SM predictions in the b-vetoed single lepton control regions before and after performing the simultaneous fit to the different control regions and signal region. Each bin shows the event yields divided by the width of the bin. The figure corresponds to the single electron b-vetoed control region, and corresponds to the loose category of the control regions. The blue solid line represents the sum of the SM contributions normalized to their fitted yields. The red dashed line represents the sum of the SM contributions normalized to the prediction. The stacked histograms show the individual fitted SM contributions. The lower panel shows the ratio of data to fitted prediction. The gray band on the ratio indicates the one standard deviation uncertainty on the prediction after propagating all the systematic uncertainties and their correlations in the fit. |
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Figure 6-b:
Comparison between data and SM predictions in the b-vetoed single lepton control regions before and after performing the simultaneous fit to the different control regions and signal region. Each bin shows the event yields divided by the width of the bin. The figure corresponds to the single electron b-vetoed control region, and corresponds to the tight category of the control regions. The blue solid line represents the sum of the SM contributions normalized to their fitted yields. The red dashed line represents the sum of the SM contributions normalized to the prediction. The stacked histograms show the individual fitted SM contributions. The lower panel shows the ratio of data to fitted prediction. The gray band on the ratio indicates the one standard deviation uncertainty on the prediction after propagating all the systematic uncertainties and their correlations in the fit. |
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Figure 6-c:
Comparison between data and SM predictions in the b-vetoed single lepton control regions before and after performing the simultaneous fit to the different control regions and signal region. Each bin shows the event yields divided by the width of the bin. The figure corresponds to the single muon b-vetoed control region, and corresponds to the loose category of the control regions. The blue solid line represents the sum of the SM contributions normalized to their fitted yields. The red dashed line represents the sum of the SM contributions normalized to the prediction. The stacked histograms show the individual fitted SM contributions. The lower panel shows the ratio of data to fitted prediction. The gray band on the ratio indicates the one standard deviation uncertainty on the prediction after propagating all the systematic uncertainties and their correlations in the fit. |
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Figure 6-d:
Comparison between data and SM predictions in the b-vetoed single lepton control regions before and after performing the simultaneous fit to the different control regions and signal region. Each bin shows the event yields divided by the width of the bin. The figure corresponds to the single muon b-vetoed control region, and corresponds to the tight category of the control regions. The blue solid line represents the sum of the SM contributions normalized to their fitted yields. The red dashed line represents the sum of the SM contributions normalized to the prediction. The stacked histograms show the individual fitted SM contributions. The lower panel shows the ratio of data to fitted prediction. The gray band on the ratio indicates the one standard deviation uncertainty on the prediction after propagating all the systematic uncertainties and their correlations in the fit. |
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Figure 7:
Comparison between data and SM predictions in the b-tagged single lepton control regions before and after performing the simultaneous fit to the different control regions and signal region. Each bin shows the event yields divided by the width of the bin. The upper row of figures corresponds to the single electron b-tagged control region, and lower row to the single muon b-tagged control region. The left (right) column of figures corresponds to the loose (tight) category of the control regions. The blue solid line represents the sum of the SM contributions normalized to their fitted yields. The red dashed line represents the sum of the SM contributions normalized to the prediction. The stacked histograms show the individual fitted SM contributions. The lower panel of each figure shows the ratio of data to fitted prediction. The gray band on the ratio indicates the one standard deviation uncertainty on the prediction after propagating all the systematic uncertainties and their correlations in the fit. |
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Figure 7-a:
Comparison between data and SM predictions in the b-tagged single lepton control regions before and after performing the simultaneous fit to the different control regions and signal region. Each bin shows the event yields divided by the width of the bin. The figure corresponds to the single electron b-tagged control region, and corresponds to the loose category of the control regions. The blue solid line represents the sum of the SM contributions normalized to their fitted yields. The red dashed line represents the sum of the SM contributions normalized to the prediction. The stacked histograms show the individual fitted SM contributions. The lower panel shows the ratio of data to fitted prediction. The gray band on the ratio indicates the one standard deviation uncertainty on the prediction after propagating all the systematic uncertainties and their correlations in the fit. |
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Figure 7-b:
Comparison between data and SM predictions in the b-tagged single lepton control regions before and after performing the simultaneous fit to the different control regions and signal region. Each bin shows the event yields divided by the width of the bin. The figure corresponds to the single electron b-tagged control region, and corresponds to the tight category of the control regions. The blue solid line represents the sum of the SM contributions normalized to their fitted yields. The red dashed line represents the sum of the SM contributions normalized to the prediction. The stacked histograms show the individual fitted SM contributions. The lower panel shows the ratio of data to fitted prediction. The gray band on the ratio indicates the one standard deviation uncertainty on the prediction after propagating all the systematic uncertainties and their correlations in the fit. |
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Figure 7-c:
Comparison between data and SM predictions in the b-tagged single lepton control regions before and after performing the simultaneous fit to the different control regions and signal region. Each bin shows the event yields divided by the width of the bin. The figure corresponds to the single muon b-tagged control region, and corresponds to the loose category of the control regions. The blue solid line represents the sum of the SM contributions normalized to their fitted yields. The red dashed line represents the sum of the SM contributions normalized to the prediction. The stacked histograms show the individual fitted SM contributions. The lower panel shows the ratio of data to fitted prediction. The gray band on the ratio indicates the one standard deviation uncertainty on the prediction after propagating all the systematic uncertainties and their correlations in the fit. |
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Figure 7-d:
Comparison between data and SM predictions in the b-tagged single lepton control regions before and after performing the simultaneous fit to the different control regions and signal region. Each bin shows the event yields divided by the width of the bin. The figure corresponds to the single muon b-tagged control region, and corresponds to the tight category of the control regions. The blue solid line represents the sum of the SM contributions normalized to their fitted yields. The red dashed line represents the sum of the SM contributions normalized to the prediction. The stacked histograms show the individual fitted SM contributions. The lower panel shows the ratio of data to fitted prediction. The gray band on the ratio indicates the one standard deviation uncertainty on the prediction after propagating all the systematic uncertainties and their correlations in the fit. |
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Figure 8:
Distribution of $ {{p_{\mathrm {T}}} ^\text {miss}} $ from SM backgrounds and data in the signal region after simultaneously fitting the signal region and all control regions. Each bin shows the event yields divided by the width of the bin. The left (right) figure corresponds to the loose (tight) category of the signal region. The stacked histograms show the individual fitted SM background contributions. The blue solid line represents the sum of the SM background contributions normalized to their fitted yields. The red dashed line represents the sum of the SM background contributions normalized to the prediction. The lower panel of each figure shows the ratio of data to fitted prediction. The gray band on the ratio indicates the one standard deviation uncertainty on the prediction after propagating all the systematic uncertainties and their correlations in the fit. |
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Figure 8-a:
Distribution of $ {{p_{\mathrm {T}}} ^\text {miss}} $ from SM backgrounds and data in the signal region after simultaneously fitting the signal region and all control regions. Each bin shows the event yields divided by the width of the bin. The figure corresponds to the loose category of the signal region. The stacked histograms show the individual fitted SM background contributions. The blue solid line represents the sum of the SM background contributions normalized to their fitted yields. The red dashed line represents the sum of the SM background contributions normalized to the prediction. The lower panel shows the ratio of data to fitted prediction. The gray band on the ratio indicates the one standard deviation uncertainty on the prediction after propagating all the systematic uncertainties and their correlations in the fit. |
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Figure 8-b:
Distribution of $ {{p_{\mathrm {T}}} ^\text {miss}} $ from SM backgrounds and data in the signal region after simultaneously fitting the signal region and all control regions. Each bin shows the event yields divided by the width of the bin. The figure corresponds to the tight category of the signal region. The stacked histograms show the individual fitted SM background contributions. The blue solid line represents the sum of the SM background contributions normalized to their fitted yields. The red dashed line represents the sum of the SM background contributions normalized to the prediction. The lower panel shows the ratio of data to fitted prediction. The gray band on the ratio indicates the one standard deviation uncertainty on the prediction after propagating all the systematic uncertainties and their correlations in the fit. |
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Figure 9:
Results for the FCNC interpretation presented in the two-dimensional plane spanned by the mediator and DM masses. The mediator is assumed to have purely vector couplings to quarks and DM particles. The observed exclusion range (gold solid line) is shown. The gold dashed lines show the cases in which the predicted cross section is shifted by the assigned theoretical uncertainty. The expected exclusion range is indicated by a black solid line, demonstrating the search sensitivity of the analysis. The experimental uncertainties are shown in black dashed lines. |
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Figure 10:
Results for the FCNC interpretation presented in the two-dimensional plane spanned by the mediator and DM masses. The mediator is assumed to have purely axial couplings to quarks and DM particles. The observed exclusion range (gold solid line) is shown. The gold dashed lines show the cases in which the predicted cross section is shifted by the assigned theoretical uncertainty. The expected exclusion range is indicated by a black solid line, demonstrating the search sensitivity of the analysis. The experimental uncertainties are shown in black dashed lines. |
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Figure 11:
Results for the FCNC interpretation presented in the two-dimensional plane spanned by the mediator mass and the coupling between the mediator and DM (upper) or quarks (lower). The mediator is assumed to have purely vector couplings. The observed exclusion range (gold solid line) is shown. The gold dashed lines show the cases in which the predicted cross section is shifted by the assigned theoretical uncertainty. The expected exclusion range is indicated by a black solid line, demonstrating the search sensitivity of the analysis. The experimental uncertainties are shown in black dashed lines. |
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Figure 11-a:
Results for the FCNC interpretation presented in the two-dimensional plane spanned by the mediator mass and the coupling between the mediator and DM. The mediator is assumed to have purely vector couplings. The observed exclusion range (gold solid line) is shown. The gold dashed lines show the cases in which the predicted cross section is shifted by the assigned theoretical uncertainty. The expected exclusion range is indicated by a black solid line, demonstrating the search sensitivity of the analysis. The experimental uncertainties are shown in black dashed lines. |
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Figure 11-b:
Results for the FCNC interpretation presented in the two-dimensional plane spanned by the mediator mass and the coupling between the mediator and quarks. The mediator is assumed to have purely vector couplings. The observed exclusion range (gold solid line) is shown. The gold dashed lines show the cases in which the predicted cross section is shifted by the assigned theoretical uncertainty. The expected exclusion range is indicated by a black solid line, demonstrating the search sensitivity of the analysis. The experimental uncertainties are shown in black dashed lines. |
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Figure 12:
Results for the FCNC interpretation presented in the two-dimensional plane spanned by the mediator mass and the coupling between the mediator and DM (upper) or quarks (lower). The mediator is assumed to have purely axial couplings. The observed exclusion range (gold solid line) is shown. The gold dashed lines show the cases in which the predicted cross section is shifted by the assigned theoretical uncertainty. The expected exclusion range is indicated by a black solid line, demonstrating the search sensitivity of the analysis. The experimental uncertainties are shown in black dashed lines. |
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Figure 12-a:
Results for the FCNC interpretation presented in the two-dimensional plane spanned by the mediator mass and the coupling between the mediator and DM. The mediator is assumed to have purely axial couplings. The observed exclusion range (gold solid line) is shown. The gold dashed lines show the cases in which the predicted cross section is shifted by the assigned theoretical uncertainty. The expected exclusion range is indicated by a black solid line, demonstrating the search sensitivity of the analysis. The experimental uncertainties are shown in black dashed lines. |
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Figure 12-b:
Results for the FCNC interpretation presented in the two-dimensional plane spanned by the mediator mass and the coupling between the mediator and quarks. The mediator is assumed to have purely axial couplings. The observed exclusion range (gold solid line) is shown. The gold dashed lines show the cases in which the predicted cross section is shifted by the assigned theoretical uncertainty. The expected exclusion range is indicated by a black solid line, demonstrating the search sensitivity of the analysis. The experimental uncertainties are shown in black dashed lines. |
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Figure 13:
Upper limits at 95% CL on the mass of the scalar particle $\phi $ in the resonant model, assuming fixed $a_\mathrm {q} = b_\mathrm {q} = $ 0.1 and $a_\psi = b_\psi = $ 0.2. The green and yellow bands represent one and two standard deviations of experimental uncertainties, respectively. The red hatched band represents the signal cross section uncertainty as a function of $m_\phi $. |
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Figure A1:
Inclusive distribution of the transverse momentum of the mediator boson V in the FCNC monotop production mechanism, both at leading-order (LO) and next-to-leading order (NLO) accuracy in QCD, assuming couplings of $g_\mathrm {q}^ {\mathrm {V}}= $ 0.25 and $g_\chi ^ {\mathrm {V}}= $ 1 and masses of 1.75 TeV and 1 GeV for V and the fermionic DM particle $\chi $, respectively. Shaded bands around the central predictions correspond to independent variations of the nominal factorization and renormalization scale $H_\mathrm {T}/2$ by factors of 2 and $1/2$. While the NLO case exhibits a softer spectrum for $ {p_{\mathrm {T}}} ^\mathrm {V}$ than the LO computation, which should result in a relatively softer $ {{p_{\mathrm {T}}} ^\text {miss}} $, the inclusive cross section increases by about 25% (from 24.8 fb at LO to 31.4 fb at NLO). |
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Figure A2:
Distribution of ${{p_{\mathrm {T}}} ^\text {miss}}$ in monotop signal models. On the left is shown the FCNC model for various values of $m_ {\mathrm {V}}$; on the right is the scalar resonance model for various values of $m_\phi $. |
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Figure A2-a:
Distribution of ${{p_{\mathrm {T}}} ^\text {miss}}$ in monotop signal models. Is shown the FCNC model for various values of $m_ {\mathrm {V}}$. |
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Figure A2-b:
Distribution of ${{p_{\mathrm {T}}} ^\text {miss}}$ in monotop signal models. Is shown the scalar resonance model for various values of $m_\phi $. |
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Figure A3:
Distribution of $ {{p_{\mathrm {T}}} ^\text {miss}} $ from SM backgrounds and data in the loose category of the signal region after fitting the control regions only. Each bin shows the event yields divided by the width of the bin. The stacked histograms show the individual SM background distributions after the fit is performed. The lower panel of the figure shows the ratio of data to fitted prediction. The gray band on the ratio indicates the one standard deviation uncertainty on the prediction after propagating all the systematic uncertainties and their correlations in the fit. |
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Figure A4:
Distribution of $ {{p_{\mathrm {T}}} ^\text {miss}} $ from SM backgrounds and data in the tight category of the signal region after fitting the control regions only. Each bin shows the event yields divided by the width of the bin. The stacked histograms show the individual SM background distributions after the fit is performed. The lower panel of the figure shows the ratio of data to fitted prediction. The gray band on the ratio indicates the one standard deviation uncertainty on the prediction after propagating all the systematic uncertainties and their correlations in the fit. |
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Figure A5:
Correlations between background predictions in each of the bins of the loose signal region, after performing the fit in only the control regions. |
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Figure A6:
Correlations between background predictions in each of the bins of the tight signal region, after having performed the fit in only the control regions. |
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Figure A7:
The maximum excluded mediator mass at 95% CL as a function of vector couplings to DM and quarks. This plot fixes $m_\chi = $ 1 GeV and $g_\chi ^\mathrm {A} = g_\mathrm {q}^\mathrm {A}= $ 0. Masses up to 2.5 TeV are excluded given sufficiently large coupling choices. |
| Tables | |
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Table 1:
Summary of the selection criteria used in the SR and CRs. Symbols $\{\mathrm {b}\}$ and $\{\ell \}$ refer to cases where the b quark or lepton are not identified. $N_ {\mathrm {e}}$, $N_\mu $, and $N_\gamma $ refer to the number of selected electrons, muons, and photons, respectively. The number of b-tagged isolated jets is denoted with $N_{\text {b-tag}}^\text {iso}$. |
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Table A1:
Predicted SM backgrounds and yields in data in each bin of the loose signal region, after performing the fit in the control regions only. "Minor backgrounds'' refers to the diboson, single t, and QCD multijet backgrounds. |
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Table A2:
Predicted SM backgrounds and yields in data in each bin of the tight signal region, after performing the fit in the control regions only. "Minor backgrounds'' refers to the diboson, single t, and QCD multijet backgrounds. |
| Summary |
|
A search is reported for dark matter events with large transverse momentum imbalance and a hadronically decaying top quark. New t-tagging techniques are presented and utilized to identify jets from the Lorentz-boosted top quark. The data are found to be in agreement with the standard model prediction for the expected background. Results are interpreted in terms of limits on the production cross section of dark matter (DM) particles via a flavor-changing neutral current interaction or via the decay of a colored scalar resonance. Other experimental searches [60] probe the production of DM via neutral currents, under the assumption that flavor is conserved. This analysis augments these searches by considering DM production in scenarios that violate flavor conservation. Assuming $ m_\chi = $ 1 GeV, $ g^{\mathrm{V}}_\mathrm{u}= $ 0.25, and $ g^{\mathrm{V}}_{\chi}= $ 1, spin-1 mediators with masses 0.2 $ < m_{\mathrm{V}} < $ 1.75 TeV in the FCNC model are excluded at the 95% confidence level. Scalar resonances decaying to DM and a top quark are excluded in the range 1.5 $ < m_\phi < $ 3.4 TeV, assuming $m_\psi = $ 100 GeV. |
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