CMS-SUS-16-041 ; CERN-EP-2017-243 | ||
Search for supersymmetry in events with at least three electrons or muons, jets, and missing transverse momentum in proton-proton collisions at $\sqrt{s} = $ 13 TeV | ||
CMS Collaboration | ||
23 October 2017 | ||
JHEP 02 (2018) 067 | ||
Abstract: A search for new physics is carried out in events with at least three electrons or muons in any combination, jets, and missing transverse momentum. Results are based on the sample of proton-proton collision data produced by the LHC at a center-of-mass energy of 13 TeV and collected by the CMS experiment in 2016. The data sample analyzed corresponds to an integrated luminosity of 35.9 fb$^{-1}$. Events are classified according to the number of b jets, missing transverse momentum, hadronic transverse momentum, and the invariant mass of same-flavor dilepton pairs with opposite charge. No significant excess above the expected standard model background is observed. Exclusion limits at 95% confidence level are computed for four different supersymmetric simplified models with pair production of gluinos or third-generation squarks. In the model with gluino pair production, with subsequent decays into a top quark-antiquark pair and a neutralino, gluinos with masses smaller than 1610 GeV are excluded for a massless lightest supersymmetric particle. In the case of bottom squark pair production, the bottom squark masses are excluded up to 840 GeV for charginos lighter than 200 GeV. For a simplified model of heavy top squark pair production, the $\mathrm{\widetilde{\text{t}}_2}$ mass is excluded up to 720, 780, or 710 GeV for models with an exclusive $\mathrm{\widetilde{\text{t}}_2}\rightarrow\mathrm{\widetilde{\text{t}}_1}\mathrm{H}$ decay, an exclusive $\mathrm{\widetilde{\text{t}}_2}\rightarrow\mathrm{\widetilde{\text{t}}_1}\mathrm{Z}$ decay, or an equally probable mix of those two decays. In order to provide a simplified version of the analysis for easier interpretation, a small set of aggregate signal regions also has been defined, providing a compromise between simplicity and analysis sensitivity. | ||
Links: e-print arXiv:1710.09154 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; CADI line (restricted) ; |
Figures & Tables | Summary | Additional Tables | References | CMS Publications |
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Additional information on efficiencies needed for reinterpretation of
these results are available here.
Additional technical material for CMS speakers can be found here |
Figures | |
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Figure 1:
Diagrams for models with gluino pair production leading to four top quarks, T1tttt (upper left), or four quarks and two vector bosons, T5qqqqVV (upper right) in the final state, in both cases accompanied by two LSPs. Models of bottom, T6ttWW, and top squark, T6ttHZ, pair production lead to two top quarks, two LSPs and either two W bosons (lower left) or two neutral bosons as SM Higgs (H) and/or Z bosons (lower right). |
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Figure 1-a:
Diagram for the T1tttt model with gluino pair production leading to |
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Figure 1-b:
Diagram for the T5qqqqVV model with gluino pair production leading to four quarks and two vector bosons in the final state, accompanied by two LSPs. |
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Figure 1-c:
Diagram for the T6ttWW model of bottom squark pair production with two top quarks, two LSPs and either two W bosons. |
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Figure 1-d:
Diagram for the T6ttHZ model of top squark pair production with two top quarks, two LSPs and two neutral bosons as SM Higgs (H) and/or Z bosons. |
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Figure 2:
Background prediction and the observed event yields in the key observables for the off-Z baseline selection: the number of jets and b jets, ${H_{\mathrm {T}}}$, ${M_{\text {T}}}$, ${{p_{\mathrm {T}}} ^\text {miss}}$, the lepton ${p_{\mathrm {T}}}$ spectra and the event yields by flavor category are shown. The background events containing top quark(s) in association with a W, Z or Higgs boson, except ${{\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{Z}}$, or another pair of top quarks are denoted as ${\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{X}$. The last bin includes the overflow events, and the hatched area represents the statistical and combined systematic uncertainties in the prediction. The lower panels show the ratio of the observed and predicted yields in each bin. For illustration the yields, multiplied by a factor 10, for two signal mass points in the T6ttHZ model, where the $\mathcal {B}(\tilde{\mathrm {t}}_2 \rightarrow \tilde{\mathrm {t}}_1 \mathrm{H} ) =$ 100%, are displayed for non-compressed ($ m(\tilde{\mathrm {t}}_2) = $ 700 GeV and $ m(\tilde{\mathrm {t}}_1) = $175 GeV) and compressed ($ m(\tilde{\mathrm {t}}_2) = $ 600 GeV and $ m(\tilde{\mathrm {t}}_1) = $ 425 GeV) scenarios. |
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Figure 2-a:
Background prediction and the observed event yields in the number of jets for the off-Z baseline selection. The background events containing top quark(s) in association with a W, Z or Higgs boson, except ${{\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{Z}}$, or another pair of top quarks are denoted as ${\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{X}$. The last bin includes the overflow events, and the hatched area represents the statistical and combined systematic uncertainties in the prediction. The lower panel shows the ratio of the observed and predicted yields in each bin. For illustration the yields, multiplied by a factor 10, for two signal mass points in the T6ttHZ model, where the $\mathcal {B}(\tilde{\mathrm {t}}_2 \rightarrow \tilde{\mathrm {t}}_1 \mathrm{H} ) =$ 100%, are displayed for non-compressed ($ m(\tilde{\mathrm {t}}_2) = $ 700 GeV and $ m(\tilde{\mathrm {t}}_1) = $175 GeV) and compressed ($ m(\tilde{\mathrm {t}}_2) = $ 600 GeV and $ m(\tilde{\mathrm {t}}_1) = $ 425 GeV) scenarios. |
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Figure 2-b:
Background prediction and the observed event yields in the number of b jets for the off-Z baseline selection. The background events containing top quark(s) in association with a W, Z or Higgs boson, except ${{\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{Z}}$, or another pair of top quarks are denoted as ${\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{X}$. The last bin includes the overflow events, and the hatched area represents the statistical and combined systematic uncertainties in the prediction. The lower panel shows the ratio of the observed and predicted yields in each bin. For illustration the yields, multiplied by a factor 10, for two signal mass points in the T6ttHZ model, where the $\mathcal {B}(\tilde{\mathrm {t}}_2 \rightarrow \tilde{\mathrm {t}}_1 \mathrm{H} ) =$ 100%, are displayed for non-compressed ($ m(\tilde{\mathrm {t}}_2) = $ 700 GeV and $ m(\tilde{\mathrm {t}}_1) = $175 GeV) and compressed ($ m(\tilde{\mathrm {t}}_2) = $ 600 GeV and $ m(\tilde{\mathrm {t}}_1) = $ 425 GeV) scenarios. |
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Figure 2-c:
Background prediction and the observed event yields in ${H_{\mathrm {T}}}$ for the off-Z baseline selection. The background events containing top quark(s) in association with a W, Z or Higgs boson, except ${{\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{Z}}$, or another pair of top quarks are denoted as ${\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{X}$. The last bin includes the overflow events, and the hatched area represents the statistical and combined systematic uncertainties in the prediction. The lower panel shows the ratio of the observed and predicted yields in each bin. For illustration the yields, multiplied by a factor 10, for two signal mass points in the T6ttHZ model, where the $\mathcal {B}(\tilde{\mathrm {t}}_2 \rightarrow \tilde{\mathrm {t}}_1 \mathrm{H} ) =$ 100%, are displayed for non-compressed ($ m(\tilde{\mathrm {t}}_2) = $ 700 GeV and $ m(\tilde{\mathrm {t}}_1) = $175 GeV) and compressed ($ m(\tilde{\mathrm {t}}_2) = $ 600 GeV and $ m(\tilde{\mathrm {t}}_1) = $ 425 GeV) scenarios. |
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Figure 2-d:
Background prediction and the observed event yields in ${M_{\text {T}}}$ for the off-Z baseline selection. The background events containing top quark(s) in association with a W, Z or Higgs boson, except ${{\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{Z}}$, or another pair of top quarks are denoted as ${\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{X}$. The last bin includes the overflow events, and the hatched area represents the statistical and combined systematic uncertainties in the prediction. The lower panel shows the ratio of the observed and predicted yields in each bin. For illustration the yields, multiplied by a factor 10, for two signal mass points in the T6ttHZ model, where the $\mathcal {B}(\tilde{\mathrm {t}}_2 \rightarrow \tilde{\mathrm {t}}_1 \mathrm{H} ) =$ 100%, are displayed for non-compressed ($ m(\tilde{\mathrm {t}}_2) = $ 700 GeV and $ m(\tilde{\mathrm {t}}_1) = $175 GeV) and compressed ($ m(\tilde{\mathrm {t}}_2) = $ 600 GeV and $ m(\tilde{\mathrm {t}}_1) = $ 425 GeV) scenarios. |
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Figure 2-e:
Background prediction and the observed event yields in ${{p_{\mathrm {T}}} ^\text {miss}}$ for the off-Z baseline selection. The background events containing top quark(s) in association with a W, Z or Higgs boson, except ${{\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{Z}}$, or another pair of top quarks are denoted as ${\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{X}$. The last bin includes the overflow events, and the hatched area represents the statistical and combined systematic uncertainties in the prediction. The lower panel shows the ratio of the observed and predicted yields in each bin. For illustration the yields, multiplied by a factor 10, for two signal mass points in the T6ttHZ model, where the $\mathcal {B}(\tilde{\mathrm {t}}_2 \rightarrow \tilde{\mathrm {t}}_1 \mathrm{H} ) =$ 100%, are displayed for non-compressed ($ m(\tilde{\mathrm {t}}_2) = $ 700 GeV and $ m(\tilde{\mathrm {t}}_1) = $175 GeV) and compressed ($ m(\tilde{\mathrm {t}}_2) = $ 600 GeV and $ m(\tilde{\mathrm {t}}_1) = $ 425 GeV) scenarios. |
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Figure 2-f:
Background prediction and the observed event yields in the leading lepton ${p_{\mathrm {T}}}$ for the off-Z baseline selection. The background events containing top quark(s) in association with a W, Z or Higgs boson, except ${{\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{Z}}$, or another pair of top quarks are denoted as ${\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{X}$. The last bin includes the overflow events, and the hatched area represents the statistical and combined systematic uncertainties in the prediction. The lower panel shows the ratio of the observed and predicted yields in each bin. For illustration the yields, multiplied by a factor 10, for two signal mass points in the T6ttHZ model, where the $\mathcal {B}(\tilde{\mathrm {t}}_2 \rightarrow \tilde{\mathrm {t}}_1 \mathrm{H} ) =$ 100%, are displayed for non-compressed ($ m(\tilde{\mathrm {t}}_2) = $ 700 GeV and $ m(\tilde{\mathrm {t}}_1) = $175 GeV) and compressed ($ m(\tilde{\mathrm {t}}_2) = $ 600 GeV and $ m(\tilde{\mathrm {t}}_1) = $ 425 GeV) scenarios. |
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Figure 2-g:
Background prediction and the observed event yields in the sub-leading lepton ${p_{\mathrm {T}}}$ for the off-Z baseline selection. The background events containing top quark(s) in association with a W, Z or Higgs boson, except ${{\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{Z}}$, or another pair of top quarks are denoted as ${\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{X}$. The last bin includes the overflow events, and the hatched area represents the statistical and combined systematic uncertainties in the prediction. The lower panel shows the ratio of the observed and predicted yields in each bin. For illustration the yields, multiplied by a factor 10, for two signal mass points in the T6ttHZ model, where the $\mathcal {B}(\tilde{\mathrm {t}}_2 \rightarrow \tilde{\mathrm {t}}_1 \mathrm{H} ) =$ 100%, are displayed for non-compressed ($ m(\tilde{\mathrm {t}}_2) = $ 700 GeV and $ m(\tilde{\mathrm {t}}_1) = $175 GeV) and compressed ($ m(\tilde{\mathrm {t}}_2) = $ 600 GeV and $ m(\tilde{\mathrm {t}}_1) = $ 425 GeV) scenarios. |
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Figure 2-h:
Background prediction and the observed event yields in the trailing lepton ${p_{\mathrm {T}}}$ for the off-Z baseline selection. The background events containing top quark(s) in association with a W, Z or Higgs boson, except ${{\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{Z}}$, or another pair of top quarks are denoted as ${\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{X}$. The last bin includes the overflow events, and the hatched area represents the statistical and combined systematic uncertainties in the prediction. The lower panel shows the ratio of the observed and predicted yields in each bin. For illustration the yields, multiplied by a factor 10, for two signal mass points in the T6ttHZ model, where the $\mathcal {B}(\tilde{\mathrm {t}}_2 \rightarrow \tilde{\mathrm {t}}_1 \mathrm{H} ) =$ 100%, are displayed for non-compressed ($ m(\tilde{\mathrm {t}}_2) = $ 700 GeV and $ m(\tilde{\mathrm {t}}_1) = $175 GeV) and compressed ($ m(\tilde{\mathrm {t}}_2) = $ 600 GeV and $ m(\tilde{\mathrm {t}}_1) = $ 425 GeV) scenarios. |
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Figure 2-i:
Background prediction and the observed event yields in the event yields by flavor category for the off-Z baseline selection. The background events containing top quark(s) in association with a W, Z or Higgs boson, except ${{\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{Z}}$, or another pair of top quarks are denoted as ${\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{X}$. The last bin includes the overflow events, and the hatched area represents the statistical and combined systematic uncertainties in the prediction. The lower panel shows the ratio of the observed and predicted yields in each bin. For illustration the yields, multiplied by a factor 10, for two signal mass points in the T6ttHZ model, where the $\mathcal {B}(\tilde{\mathrm {t}}_2 \rightarrow \tilde{\mathrm {t}}_1 \mathrm{H} ) =$ 100%, are displayed for non-compressed ($ m(\tilde{\mathrm {t}}_2) = $ 700 GeV and $ m(\tilde{\mathrm {t}}_1) = $175 GeV) and compressed ($ m(\tilde{\mathrm {t}}_2) = $ 600 GeV and $ m(\tilde{\mathrm {t}}_1) = $ 425 GeV) scenarios. |
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Figure 3:
Background prediction and the observed event yields in the key observables of the on-Z baseline selection: the number of jets and b jets, ${H_{\mathrm {T}}}$, ${M_{\text {T}}}$, ${{p_{\mathrm {T}}} ^\text {miss}}$, the lepton ${p_{\mathrm {T}}}$ spectra and the event yields by flavor category are shown. The background events containing top quark(s) in association with a W, Z or Higgs boson, except ${{\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{Z}}$, or another pair of top quarks are denoted as ${\mathrm{t} \mathrm{\bar{t}}} \mathrm{X}$. The last bin includes the overflow events, and the hatched area represents the combined statistical and systematic uncertainties in the prediction. The lower panels show the ratio of the observed and predicted yields in each bin. For illustration the yields, multiplied by a factor 10, for two signal mass points in the T6ttHZ model, where the $\mathcal {B}(\tilde{\text {t}}_2 \rightarrow \tilde{\text {t}}_1 \mathrm{Z} ) = $ 100%, are displayed for non-compressed ($m(\tilde{\text {t}}_2) = $ 700 GeV and $ m(\tilde{\text {t}}_1) = $ 175 GeV) and compressed ($ m(\tilde{\text {t}}_2) = $ 600 GeV and $ m(\tilde{\text {t}}_1) = $ 550 GeV) scenarios. |
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Figure 3-a:
Background prediction and the observed event yields in the number of jets for the on-Z baseline selection. The background events containing top quark(s) in association with a W, Z or Higgs boson, except ${{\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{Z}}$, or another pair of top quarks are denoted as ${\mathrm{t} \mathrm{\bar{t}}} \mathrm{X}$. The last bin includes the overflow events, and the hatched area represents the combined statistical and systematic uncertainties in the prediction. The lower panel shows the ratio of the observed and predicted yields in each bin. For illustration the yields, multiplied by a factor 10, for two signal mass points in the T6ttHZ model, where the $\mathcal {B}(\tilde{\text {t}}_2 \rightarrow \tilde{\text {t}}_1 \mathrm{Z} ) = $ 100%, are displayed for non-compressed ($m(\tilde{\text {t}}_2) = $ 700 GeV and $ m(\tilde{\text {t}}_1) = $ 175 GeV) and compressed ($ m(\tilde{\text {t}}_2) = $ 600 GeV and $ m(\tilde{\text {t}}_1) = $ 550 GeV) scenarios. |
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Figure 3-b:
Background prediction and the observed event yields in the number of b jets for the on-Z baseline selection. The background events containing top quark(s) in association with a W, Z or Higgs boson, except ${{\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{Z}}$, or another pair of top quarks are denoted as ${\mathrm{t} \mathrm{\bar{t}}} \mathrm{X}$. The last bin includes the overflow events, and the hatched area represents the combined statistical and systematic uncertainties in the prediction. The lower panel shows the ratio of the observed and predicted yields in each bin. For illustration the yields, multiplied by a factor 10, for two signal mass points in the T6ttHZ model, where the $\mathcal {B}(\tilde{\text {t}}_2 \rightarrow \tilde{\text {t}}_1 \mathrm{Z} ) = $ 100%, are displayed for non-compressed ($m(\tilde{\text {t}}_2) = $ 700 GeV and $ m(\tilde{\text {t}}_1) = $ 175 GeV) and compressed ($ m(\tilde{\text {t}}_2) = $ 600 GeV and $ m(\tilde{\text {t}}_1) = $ 550 GeV) scenarios. |
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Figure 3-c:
Background prediction and the observed event yields in ${H_{\mathrm {T}}}$ for the on-Z baseline selection. The background events containing top quark(s) in association with a W, Z or Higgs boson, except ${{\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{Z}}$, or another pair of top quarks are denoted as ${\mathrm{t} \mathrm{\bar{t}}} \mathrm{X}$. The last bin includes the overflow events, and the hatched area represents the combined statistical and systematic uncertainties in the prediction. The lower panel shows the ratio of the observed and predicted yields in each bin. For illustration the yields, multiplied by a factor 10, for two signal mass points in the T6ttHZ model, where the $\mathcal {B}(\tilde{\text {t}}_2 \rightarrow \tilde{\text {t}}_1 \mathrm{Z} ) = $ 100%, are displayed for non-compressed ($m(\tilde{\text {t}}_2) = $ 700 GeV and $ m(\tilde{\text {t}}_1) = $ 175 GeV) and compressed ($ m(\tilde{\text {t}}_2) = $ 600 GeV and $ m(\tilde{\text {t}}_1) = $ 550 GeV) scenarios. |
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Figure 3-d:
Background prediction and the observed event yields in ${M_{\text {T}}}$ for the on-Z baseline selection. The background events containing top quark(s) in association with a W, Z or Higgs boson, except ${{\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{Z}}$, or another pair of top quarks are denoted as ${\mathrm{t} \mathrm{\bar{t}}} \mathrm{X}$. The last bin includes the overflow events, and the hatched area represents the combined statistical and systematic uncertainties in the prediction. The lower panel shows the ratio of the observed and predicted yields in each bin. For illustration the yields, multiplied by a factor 10, for two signal mass points in the T6ttHZ model, where the $\mathcal {B}(\tilde{\text {t}}_2 \rightarrow \tilde{\text {t}}_1 \mathrm{Z} ) = $ 100%, are displayed for non-compressed ($m(\tilde{\text {t}}_2) = $ 700 GeV and $ m(\tilde{\text {t}}_1) = $ 175 GeV) and compressed ($ m(\tilde{\text {t}}_2) = $ 600 GeV and $ m(\tilde{\text {t}}_1) = $ 550 GeV) scenarios. |
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Figure 3-e:
Background prediction and the observed event yields in ${{p_{\mathrm {T}}} ^\text {miss}}$ for the on-Z baseline selection. The background events containing top quark(s) in association with a W, Z or Higgs boson, except ${{\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{Z}}$, or another pair of top quarks are denoted as ${\mathrm{t} \mathrm{\bar{t}}} \mathrm{X}$. The last bin includes the overflow events, and the hatched area represents the combined statistical and systematic uncertainties in the prediction. The lower panel shows the ratio of the observed and predicted yields in each bin. For illustration the yields, multiplied by a factor 10, for two signal mass points in the T6ttHZ model, where the $\mathcal {B}(\tilde{\text {t}}_2 \rightarrow \tilde{\text {t}}_1 \mathrm{Z} ) = $ 100%, are displayed for non-compressed ($m(\tilde{\text {t}}_2) = $ 700 GeV and $ m(\tilde{\text {t}}_1) = $ 175 GeV) and compressed ($ m(\tilde{\text {t}}_2) = $ 600 GeV and $ m(\tilde{\text {t}}_1) = $ 550 GeV) scenarios. |
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Figure 3-f:
Background prediction and the observed event yields in the leading lepton ${p_{\mathrm {T}}}$ for the on-Z baseline selection. The background events containing top quark(s) in association with a W, Z or Higgs boson, except ${{\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{Z}}$, or another pair of top quarks are denoted as ${\mathrm{t} \mathrm{\bar{t}}} \mathrm{X}$. The last bin includes the overflow events, and the hatched area represents the combined statistical and systematic uncertainties in the prediction. The lower panel shows the ratio of the observed and predicted yields in each bin. For illustration the yields, multiplied by a factor 10, for two signal mass points in the T6ttHZ model, where the $\mathcal {B}(\tilde{\text {t}}_2 \rightarrow \tilde{\text {t}}_1 \mathrm{Z} ) = $ 100%, are displayed for non-compressed ($m(\tilde{\text {t}}_2) = $ 700 GeV and $ m(\tilde{\text {t}}_1) = $ 175 GeV) and compressed ($ m(\tilde{\text {t}}_2) = $ 600 GeV and $ m(\tilde{\text {t}}_1) = $ 550 GeV) scenarios. |
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Figure 3-g:
Background prediction and the observed event yields in the sub-leading lepton ${p_{\mathrm {T}}}$ for the on-Z baseline selection. The background events containing top quark(s) in association with a W, Z or Higgs boson, except ${{\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{Z}}$, or another pair of top quarks are denoted as ${\mathrm{t} \mathrm{\bar{t}}} \mathrm{X}$. The last bin includes the overflow events, and the hatched area represents the combined statistical and systematic uncertainties in the prediction. The lower panel shows the ratio of the observed and predicted yields in each bin. For illustration the yields, multiplied by a factor 10, for two signal mass points in the T6ttHZ model, where the $\mathcal {B}(\tilde{\text {t}}_2 \rightarrow \tilde{\text {t}}_1 \mathrm{Z} ) = $ 100%, are displayed for non-compressed ($m(\tilde{\text {t}}_2) = $ 700 GeV and $ m(\tilde{\text {t}}_1) = $ 175 GeV) and compressed ($ m(\tilde{\text {t}}_2) = $ 600 GeV and $ m(\tilde{\text {t}}_1) = $ 550 GeV) scenarios. |
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Figure 3-h:
Background prediction and the observed event yields in the trailing lepton ${p_{\mathrm {T}}}$ for the on-Z baseline selection. The background events containing top quark(s) in association with a W, Z or Higgs boson, except ${{\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{Z}}$, or another pair of top quarks are denoted as ${\mathrm{t} \mathrm{\bar{t}}} \mathrm{X}$. The last bin includes the overflow events, and the hatched area represents the combined statistical and systematic uncertainties in the prediction. The lower panel shows the ratio of the observed and predicted yields in each bin. For illustration the yields, multiplied by a factor 10, for two signal mass points in the T6ttHZ model, where the $\mathcal {B}(\tilde{\text {t}}_2 \rightarrow \tilde{\text {t}}_1 \mathrm{Z} ) = $ 100%, are displayed for non-compressed ($m(\tilde{\text {t}}_2) = $ 700 GeV and $ m(\tilde{\text {t}}_1) = $ 175 GeV) and compressed ($ m(\tilde{\text {t}}_2) = $ 600 GeV and $ m(\tilde{\text {t}}_1) = $ 550 GeV) scenarios. |
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Figure 3-i:
Background prediction and the observed event yields in the event yields by flavor category for the on-Z baseline selection. The background events containing top quark(s) in association with a W, Z or Higgs boson, except ${{\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{Z}}$, or another pair of top quarks are denoted as ${\mathrm{t} \mathrm{\bar{t}}} \mathrm{X}$. The last bin includes the overflow events, and the hatched area represents the combined statistical and systematic uncertainties in the prediction. The lower panel shows the ratio of the observed and predicted yields in each bin. For illustration the yields, multiplied by a factor 10, for two signal mass points in the T6ttHZ model, where the $\mathcal {B}(\tilde{\text {t}}_2 \rightarrow \tilde{\text {t}}_1 \mathrm{Z} ) = $ 100%, are displayed for non-compressed ($m(\tilde{\text {t}}_2) = $ 700 GeV and $ m(\tilde{\text {t}}_1) = $ 175 GeV) and compressed ($ m(\tilde{\text {t}}_2) = $ 600 GeV and $ m(\tilde{\text {t}}_1) = $ 550 GeV) scenarios. |
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Figure 4:
Background prediction and observed event yields in the 23 off-Z (left) and the 23 on-Z (right) signal regions. The background events containing top quark(s) in association with a W, Z or Higgs boson, except ${{\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{Z}}$, or another pair of top quarks are denoted as ${\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{X}$. The hatched area represents the statistical and systematic uncertainties on the prediction. The lower panels show the ratio of the observed and predicted yields in each bin. For illustration the yields, multiplied by a factor 10, for $ \tilde{ \mathrm{t} }_2 \rightarrow \tilde{ \mathrm{t} }_1 \mathrm{H} $ (left) and $ \tilde{ \mathrm{t} }_2 \rightarrow \tilde{ \mathrm{t} }_1 \mathrm{Z} $ (right) decays are displayed for two signal mass points in the T6ttHZ model to represent compressed and non-compressed scenarios. |
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Figure 4-a:
Background prediction and observed event yields in the 23 off-Z signal regions. The background events containing top quark(s) in association with a W, Z or Higgs boson, except ${{\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{Z}}$, or another pair of top quarks are denoted as ${\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{X}$. The hatched area represents the statistical and systematic uncertainties on the prediction. The lower panel shows the ratio of the observed and predicted yields in each bin. For illustration the yields, multiplied by a factor 10, for $ \tilde{ \mathrm{t} }_2 \rightarrow \tilde{ \mathrm{t} }_1 \mathrm{H} $ decays are displayed for two signal mass points in the T6ttHZ model to represent compressed and non-compressed scenarios. |
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Figure 4-b:
Background prediction and observed event yields in the 23 on-Z signal regions. The background events containing top quark(s) in association with a W, Z or Higgs boson, except ${{\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{Z}}$, or another pair of top quarks are denoted as ${\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{X}$. The hatched area represents the statistical and systematic uncertainties on the prediction. The lower panel shows the ratio of the observed and predicted yields in each bin. For illustration the yields, multiplied by a factor 10, for $ \tilde{ \mathrm{t} }_2 \rightarrow \tilde{ \mathrm{t} }_1 \mathrm{Z} $ decays are displayed for two signal mass points in the T6ttHZ model to represent compressed and non-compressed scenarios. |
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Figure 5:
Cross section upper limits at 95% CL in the $m_{\tilde{ \chi }^0 _1}$ versus $m_{{\mathrm{\widetilde{g}}}}$ plane for T1tttt (left) and T5qqqqVV (right) simplified models. For the latter model the branching fraction of gluino decay to neutralino or chargino is equal to 1/3 and $m_{\tilde{ \chi }^{\pm} _{1}} = m_{\tilde{ \chi }^0 _2} = 0.5(m_{\tilde{ \mathrm{g} }} + m_{\tilde{ \chi }^0_1})$. The excluded regions are to the left and below the observed and expected limit curves. The color scale indicates the excluded cross section at a given point in the mass plane. |
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Figure 5-a:
Cross section upper limits at 95% CL in the $m_{\tilde{ \chi }^0 _1}$ versus $m_{{\mathrm{\widetilde{g}}}}$ plane for T1tttt simplified model. The excluded regions are to the left and below the observed and expected limit curves. The color scale indicates the excluded cross section at a given point in the mass plane. |
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Figure 5-b:
Cross section upper limits at 95% CL in the $m_{\tilde{ \chi }^0 _1}$ versus $m_{{\mathrm{\widetilde{g}}}}$ plane for T5qqqqVV simplified model.The branching fraction of gluino decay to neutralino or chargino is equal to 1/3 and $m_{\tilde{ \chi }^{\pm} _{1}} = m_{\tilde{ \chi }^0 _2} = 0.5(m_{\tilde{ \mathrm{g} }} + m_{\tilde{ \chi }^0_1})$. The excluded regions are to the left and below the observed and expected limit curves. The color scale indicates the excluded cross section at a given point in the mass plane. |
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Figure 6:
Cross section upper limits at 95% CL in the $m_{\tilde{ \chi }^{\pm} _1}$ versus $m_{\tilde{ \mathrm{b} }_1}$ plane for T6ttWW simplified model. The mass of the neutralino is set to 50 GeV. The descriptions of the excluded regions and color scale are the same as in Fig. 5. |
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Figure 7:
Cross section upper limits at 95% CL in the $m_{\tilde{ \mathrm{t} }_1}$ versus $m_{\tilde{ \mathrm{t} }_2}$ plane for T6ttHZ simplified model. Different branching fractions of the decay $ \tilde{ \mathrm{t} }_2 \rightarrow \tilde{ \mathrm{t} }_1\mathrm{Z} $ are considered: 0% (top left), 50% (top right), and 100% (bottom). The mass difference between the lighter top squark ($\tilde{ \mathrm{t} }_1$) and a neutralino is close to the mass of the top quark. The descriptions of the excluded regions and color scale are the same as in Fig. 5. |
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Figure 7-a:
Cross section upper limits at 95% CL in the $m_{\tilde{ \mathrm{t} }_1}$ versus $m_{\tilde{ \mathrm{t} }_2}$ plane for T6ttHZ simplified model. The branching fraction of the decay $ \tilde{ \mathrm{t} }_2 \rightarrow \tilde{ \mathrm{t} }_1\mathrm{Z} $ considered is 0%. The mass difference between the lighter top squark ($\tilde{ \mathrm{t} }_1$) and a neutralino is close to the mass of the top quark. The descriptions of the excluded regions and color scale are the same as in Fig. 5. |
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Figure 7-b:
Cross section upper limits at 95% CL in the $m_{\tilde{ \mathrm{t} }_1}$ versus $m_{\tilde{ \mathrm{t} }_2}$ plane for T6ttHZ simplified model. The branching fraction of the decay $ \tilde{ \mathrm{t} }_2 \rightarrow \tilde{ \mathrm{t} }_1\mathrm{Z} $ considered is 50%. The mass difference between the lighter top squark ($\tilde{ \mathrm{t} }_1$) and a neutralino is close to the mass of the top quark. The descriptions of the excluded regions and color scale are the same as in Fig. 5. |
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Figure 7-c:
Cross section upper limits at 95% CL in the $m_{\tilde{ \mathrm{t} }_1}$ versus $m_{\tilde{ \mathrm{t} }_2}$ plane for T6ttHZ simplified model. The branching fraction of the decay $ \tilde{ \mathrm{t} }_2 \rightarrow \tilde{ \mathrm{t} }_1\mathrm{Z} $ considered is 100%. The mass difference between the lighter top squark ($\tilde{ \mathrm{t} }_1$) and a neutralino is close to the mass of the top quark. The descriptions of the excluded regions and color scale are the same as in Fig. 5. |
Tables | |
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Table 1:
Summary of all requirements used in baseline selection criteria. |
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Table 2:
Summary of the signal region definitions. The minimum $ {{p_{\mathrm {T}}} ^\text {miss}}$ requirement is raised from 50 to 70 GeV only for the on-Z SR1 and SR5. Signal regions that are further subdivided at ${M_{\text {T}}} = $ 120 GeV are indicated with $\dagger $. The search regions are mirrored for on- and off-Z categories. |
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Table 3:
Definition of the aggregate super signal regions (SSRs). This simpler classification is proposed for reinterpretations, depending on the presence of a Z boson candidate and the number of b jets, along with additional simultaneous requirements on ${M_{\text {T}}}$, ${{p_{\mathrm {T}}} ^\text {miss}}$, and ${H_{\mathrm {T}}}$. |
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Table 4:
The effect of the systematic uncertainties on the event yields of the backgrounds and signal processes. |
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Table 5:
Expected and observed yields in the off-Z search regions. The first uncertainty states the statistical uncertainty, while the second represents the systematic uncertainty. |
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Table 6:
Expected and observed yields in the on-Z search regions. The first uncertainty states the statistical uncertainty, while the second represents the systematic uncertainty. |
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Table 7:
Expected and observed yields in the super signal regions. The background events containing top quark(s) in association with a W, Z or Higgs boson, except ${{\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{Z}}$, or another pair of top quarks are denoted as ${\mathrm{t} {}\mathrm{\bar{t}}} \mathrm{X}$. The first uncertainty states the statistical uncertainty, while the second represents the systematic uncertainty. |
Summary |
A search for physics beyond the standard model in final states with at least three electrons or muons in any combination, jets, and missing transverse momentum has been presented using data collected by the CMS detector in 2016 at $\sqrt{s} = $ 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The analysis makes use of control regions in data to estimate reducible backgrounds and to validate simulations used to estimate irreducible background processes. To maximize sensitivity to a broad range of possible signal models, 46 exclusive signal regions are defined. No significant deviation from the expected standard model background is observed in any of these signal regions. The results are interpreted using a simplified gluino-pair production model that features cascade decays producing four top quarks and two neutralinos. In this model, gluinos with a mass up to 1610 GeV are excluded in the case of a massless LSP. The maximum excluded LSP mass is 900 GeV. This represents an improvement of approximately 435 and 250 GeV, respectively, compared to the exclusion limit set in a similar search based on data collected with the CMS detector in 2015, corresponding to an integrated luminosity of 2.3 fb$^{-1}$ [39]. For the simplified model of gluino-gluino production with decay to light-flavor quark jets, two vector bosons and neutralinos, gluino masses up to 1160 GeV and neutralino masses up to 650 GeV can be excluded. The limit on gluino and neutralino masses extends the corresponding limit from the previous analysis by about 335 and 150 GeV, respectively. For a simplified model of bottom squark pair production decaying to top quarks, W bosons and neutralinos, bottom squark masses up to 840 GeV are excluded for a low mass chargino, while chargino masses are excluded up to 740 GeV. These extend the previous limits by 390 and 440 GeV for each particle, respectively. Finally, for a simplified heavy top squark pair production model with further decays to two top quarks, Higgs or Z bosons, and neutralinos, the ${\widetilde{\text{t}}_2} $ mass is excluded up to 720, 710, and 780 GeV for models with an exclusive ${\widetilde{\text{t}}_2} \rightarrow {\widetilde{\text{t}}_1} \mathrm{H} $ decay, an exclusive ${\widetilde{\text{t}}_2} \rightarrow {\widetilde{\text{t}}_1} \mathrm{Z} $ decay, or an equally probable mix of those two decays, while the ${\widetilde{\text{t}}_1} $ mass is excluded up to 440, 460, and 540 GeV for the same branching fractions. This significantly improves the results obtained with the 8 TeV dataset [36]. |
Additional Tables | |
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Additional Table 1:
Cutflow table for the gluino pair production model with four top quarks in the final state, assuming gluino and LSP masses equal to 1500 and 200 GeV, respectively. The last two lines correspond to the most populated search regions. The yields correspond to the integrated luminosity of 35.9 fb$^{-1}$ and the assumed cross section for this model is 0.0142 pb. |
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Additional Table 2:
Cutflow table for the gluino pair production model with two vector bosons and light jets in the final state, assuming gluino and LSP masses equal to 1200 and 400 GeV, respectively. The last two lines correspond to the most populated search regions. The yields correspond to the integrated luminosity of 35.9 fb$^{-1}$. The assumed cross section for this model is 0.0856 pb, with branching fraction values of 2/3 and 1/3 for $ \tilde{ \mathrm{g} } \rightarrow \tilde{ \chi }^{\pm} \mathrm{ q \bar{q}' } $ and $ \tilde{ \mathrm{g} } \rightarrow \tilde{ \chi }^{0}_2 \mathrm{ q \bar{q} } $ respectively. |
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Compact Muon Solenoid LHC, CERN |
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