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| CMS-PAS-SUS-19-012 | ||
| Search for electroweak production of charginos and neutralinos in proton-proton collisions at $\sqrt{s}= $ 13 TeV | ||
| CMS Collaboration | ||
| February 2021 | ||
| Abstract: A direct search for electroweak production of charginos and neutralinos is presented. Events with three or more leptons, with up to two hadronically decaying $\tau$ leptons, or two leptons of the same charge are analyzed. The data sample consists of 137 fb$^{-1}$ of proton-proton collisions recorded with the CMS detector at the LHC. The results are interpreted in terms of several simplified models approximating a broad range of production and decay scenarios for charginos and neutralinos. A parametric neural network is used to target several of the models suffering from large backgrounds, while a search using orthogonal search regions is provided for all the models, simplifying alternative theoretical interpretations of the results. Depending on the model hypotheses, chargino and neutralino masses between 1450 GeV and 300 GeV are excluded at 95% confidence level. | ||
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Links:
CDS record (PDF) ;
CADI line (restricted) ;
These preliminary results are superseded in this paper, Submitted to JHEP. The superseded preliminary plots can be found here. |
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| Figures | |
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Figure 1:
Production of ${\tilde{\chi}^{\pm}_1} {\tilde{\chi}^0_2}$ with subsequent decays through sleptons (left) and sneutrinos (right). |
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Figure 1-a:
Production of ${\tilde{\chi}^{\pm}_1} {\tilde{\chi}^0_2}$ with subsequent decays through sleptons (left) and sneutrinos (right). |
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Figure 1-b:
Production of ${\tilde{\chi}^{\pm}_1} {\tilde{\chi}^0_2}$ with subsequent decays through sleptons (left) and sneutrinos (right). |
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Figure 2:
Production of ${\tilde{\chi}^{\pm}_1} {\tilde{\chi}^0_2}$ with subsequent decay of ${\tilde{\chi}^{\pm}_1}$ through a W boson and ${\tilde{\chi}^0_2}$ through a Z (left) or Higgs (right) boson. |
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Figure 2-a:
Production of ${\tilde{\chi}^{\pm}_1} {\tilde{\chi}^0_2}$ with subsequent decay of ${\tilde{\chi}^{\pm}_1}$ through a W boson and ${\tilde{\chi}^0_2}$ through a Z (left) or Higgs (right) boson. |
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Figure 2-b:
Production of ${\tilde{\chi}^{\pm}_1} {\tilde{\chi}^0_2}$ with subsequent decay of ${\tilde{\chi}^{\pm}_1}$ through a W boson and ${\tilde{\chi}^0_2}$ through a Z (left) or Higgs (right) boson. |
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Figure 3:
Effective neutralino pair production with decays mediated by Z or Higgs bosons. |
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Figure 3-a:
Effective neutralino pair production with decays mediated by Z or Higgs bosons. |
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Figure 3-b:
Effective neutralino pair production with decays mediated by Z or Higgs bosons. |
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Figure 3-c:
Effective neutralino pair production with decays mediated by Z or Higgs bosons. |
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Figure 4:
Observed and expected yields as a function of the output of the neural network used to search for ${\tilde{\chi}^0_1} {\tilde{\chi}^0_2}$ production with WZ mediated decays, evaluated at $ {\delta M} = $ 20 GeV (left), $ {\delta M} = $ 90 GeV (center), and $ {\delta M} = $ 600 GeV (right). |
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Figure 4-a:
Observed and expected yields as a function of the output of the neural network used to search for ${\tilde{\chi}^0_1} {\tilde{\chi}^0_2}$ production with WZ mediated decays, evaluated at $ {\delta M} = $ 20 GeV (left), $ {\delta M} = $ 90 GeV (center), and $ {\delta M} = $ 600 GeV (right). |
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Figure 4-b:
Observed and expected yields as a function of the output of the neural network used to search for ${\tilde{\chi}^0_1} {\tilde{\chi}^0_2}$ production with WZ mediated decays, evaluated at $ {\delta M} = $ 20 GeV (left), $ {\delta M} = $ 90 GeV (center), and $ {\delta M} = $ 600 GeV (right). |
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Figure 4-c:
Observed and expected yields as a function of the output of the neural network used to search for ${\tilde{\chi}^0_1} {\tilde{\chi}^0_2}$ production with WZ mediated decays, evaluated at $ {\delta M} = $ 20 GeV (left), $ {\delta M} = $ 90 GeV (center), and $ {\delta M} = $ 600 GeV (right). |
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Figure 5:
Observed and expected yields as a function of the output of the neural network used to search for ${\tilde{\chi}^0_1} {\tilde{\chi}^0_2}$ production with slepton mediated decays at $x = 0.5$, evaluated at $ {\delta M} = $ 50 GeV (left), $ {\delta M} = $ 100 GeV (center), and $ {\delta M} = $ 800 GeV (right). |
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Figure 5-a:
Observed and expected yields as a function of the output of the neural network used to search for ${\tilde{\chi}^0_1} {\tilde{\chi}^0_2}$ production with slepton mediated decays at $x = 0.5$, evaluated at $ {\delta M} = $ 50 GeV (left), $ {\delta M} = $ 100 GeV (center), and $ {\delta M} = $ 800 GeV (right). |
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Figure 5-b:
Observed and expected yields as a function of the output of the neural network used to search for ${\tilde{\chi}^0_1} {\tilde{\chi}^0_2}$ production with slepton mediated decays at $x = 0.5$, evaluated at $ {\delta M} = $ 50 GeV (left), $ {\delta M} = $ 100 GeV (center), and $ {\delta M} = $ 800 GeV (right). |
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Figure 5-c:
Observed and expected yields as a function of the output of the neural network used to search for ${\tilde{\chi}^0_1} {\tilde{\chi}^0_2}$ production with slepton mediated decays at $x = 0.5$, evaluated at $ {\delta M} = $ 50 GeV (left), $ {\delta M} = $ 100 GeV (center), and $ {\delta M} = $ 800 GeV (right). |
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Figure 6:
Observed and expected yields as a function of the output of the neural network used to search for ${\tilde{\chi}^0_1} {\tilde{\chi}^0_2}$ production with slepton mediated decays at $x = 0.05$, evaluated at $ {\delta M} = $ 50 GeV (left), $ {\delta M} = $ 100 GeV (center), and $ {\delta M} = $ 800 GeV (right). |
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Figure 6-a:
Observed and expected yields as a function of the output of the neural network used to search for ${\tilde{\chi}^0_1} {\tilde{\chi}^0_2}$ production with slepton mediated decays at $x = 0.05$, evaluated at $ {\delta M} = $ 50 GeV (left), $ {\delta M} = $ 100 GeV (center), and $ {\delta M} = $ 800 GeV (right). |
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Figure 6-b:
Observed and expected yields as a function of the output of the neural network used to search for ${\tilde{\chi}^0_1} {\tilde{\chi}^0_2}$ production with slepton mediated decays at $x = 0.05$, evaluated at $ {\delta M} = $ 50 GeV (left), $ {\delta M} = $ 100 GeV (center), and $ {\delta M} = $ 800 GeV (right). |
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Figure 6-c:
Observed and expected yields as a function of the output of the neural network used to search for ${\tilde{\chi}^0_1} {\tilde{\chi}^0_2}$ production with slepton mediated decays at $x = 0.05$, evaluated at $ {\delta M} = $ 50 GeV (left), $ {\delta M} = $ 100 GeV (center), and $ {\delta M} = $ 800 GeV (right). |
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Figure 7:
Observed and expected yields as a function of the output of the neural network used to search for ${\tilde{\chi}^0_1} {\tilde{\chi}^0_2}$ production with slepton mediated decays at $x = 0.95$, evaluated at $ {\delta M} = $ 50 GeV (left), $ {\delta M} = $ 100 GeV (center), and $ {\delta M} = $ 800 GeV (right). |
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Figure 7-a:
Observed and expected yields as a function of the output of the neural network used to search for ${\tilde{\chi}^0_1} {\tilde{\chi}^0_2}$ production with slepton mediated decays at $x = 0.95$, evaluated at $ {\delta M} = $ 50 GeV (left), $ {\delta M} = $ 100 GeV (center), and $ {\delta M} = $ 800 GeV (right). |
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Figure 7-b:
Observed and expected yields as a function of the output of the neural network used to search for ${\tilde{\chi}^0_1} {\tilde{\chi}^0_2}$ production with slepton mediated decays at $x = 0.95$, evaluated at $ {\delta M} = $ 50 GeV (left), $ {\delta M} = $ 100 GeV (center), and $ {\delta M} = $ 800 GeV (right). |
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Figure 7-c:
Observed and expected yields as a function of the output of the neural network used to search for ${\tilde{\chi}^0_1} {\tilde{\chi}^0_2}$ production with slepton mediated decays at $x = 0.95$, evaluated at $ {\delta M} = $ 50 GeV (left), $ {\delta M} = $ 100 GeV (center), and $ {\delta M} = $ 800 GeV (right). |
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Figure 8:
Observed and expected yields across the search regions in events with two same-sign light leptons (2lSS). Signal models corresponding to ${\tilde{\chi}^0_1} {\tilde{\chi}^0_2}$ production with slepton mediated decays in the flavor democratic hypothesis for a compressed $ {\delta M} = $ 50 GeV (red line) and uncompressed $ {\delta M} = $ 500 GeV (green line) scenarios are shown superimposed. |
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Figure 9:
Observed and expected yields across the search regions in events with three light leptons at least two of which form an OSSF pair (3lA). Signal models corresponding to ${\tilde{\chi}^0_1} {\tilde{\chi}^0_2}$ production with slepton mediated decays in the flavor democratic hypothesis for a compressed $ {\delta M} = $ 50 GeV (black line) and uncompressed $ {\delta M} = $ 900 GeV (blue line) scenarios as well, and for WZ mediated decay in an uncompressed $ {\delta M} = $ 500 GeV scenario (green line) are shown superimposed. Bins labeled as "Masked'' are not considered in the interpretation of the results because of overlap with the WZ control region. |
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Figure 10:
Observed and expected yields across the search regions in events with three light leptons, none of which form an OSSF pair (3lB). Signal models corresponding to ${\tilde{\chi}^0_1} {\tilde{\chi}^0_2}$ production with WH mediated decay for scenarios corresponding to a Higgs mass like mass splitting $ {\delta M} = $ 125 GeV (black line) and a slightly less compressed $ {\delta M} = $ 500 GeV (red line) scenarios are shown superimposed. |
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Figure 11:
Observed and expected yields across the search regions in events with a $\mu ^{+}\mu ^{-}$ or $e^{+}e^{-}$ pair and an additional ${\tau _\mathrm {h}}$ (3lC). Signal models corresponding to ${\tilde{\chi}^0_1} {\tilde{\chi}^0_2}$ production with slepton mediated decays in the tau enhanced hypothesis for a compressed $ {\delta M} = $ 300 GeV (red line) and uncompressed $ {\delta M} = $ 900 GeV (green line) scenarios are shown superimposed. |
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Figure 12:
Observed and expected yields across the search regions in events with a $e^{\pm}\mu ^{\mp}$ pair and a ${\tau _\mathrm {h}}$ (3lD). Signal models corresponding to ${\tilde{\chi}^0_1} {\tilde{\chi}^0_2}$ production with slepton mediated decays in the tau dominated hypothesis for a compressed $ {\delta M} = $ 100 GeV (red line) and uncompressed $ {\delta M} = $ 500 GeV (green line) scenarios are shown superimposed. |
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Figure 13:
Observed and expected yields across the search regions in events with a same-sign light lepton pair and a ${\tau _\mathrm {h}}$ (3lE). Signal models corresponding to ${\tilde{\chi}^0_1} {\tilde{\chi}^0_2}$ production with slepton mediated decays in the tau dominated hypothesis for a compressed $ {\delta M} = $ 100 GeV (red line) and uncompressed $ {\delta M} = $ 500 GeV (green line) scenarios are shown superimposed. |
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Figure 14:
Observed and expected yields across the search regions in events with two ${\tau _\mathrm {h}}$ 's and one light lepton (3lF). Signal models corresponding to ${\tilde{\chi}^0_1} {\tilde{\chi}^0_2}$ production with slepton mediated decays in the tau dominated hypothesis for a compressed $ {\delta M} = $ 100 GeV (red line) and uncompressed $ {\delta M} = $ 500 GeV (green line) scenarios are shown superimposed. |
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Figure 15:
Observed and expected yields across the search regions in events with four light leptons, including 2 separate OSSF pairs (4lG). Signal models corresponding to higgsino pair production with scenarios corresponding to decay to ZZ (blue line, Higgsino mass of 300 GeV), HZ (red line, Higgsino mass of 150 GeV), and HH (green line, Higgsino mass of 150 GeV) are shown superimposed. |
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Figure 16:
Observed and expected yields across the search regions in events with four light leptons not forming two OSSF pairs (4lH, left), and in events with three light leptons and a ${\tau _\mathrm {h}}$ (4lI, right). Signal models corresponding to higgsino pair production with scenarios corresponding to decay to HZ (red line, Higgsino mass of 150 GeV), and HH (green line, Higgsino mass of 150 GeV) are shown superimposed. |
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Figure 16-a:
Observed and expected yields across the search regions in events with four light leptons not forming two OSSF pairs (4lH, left), and in events with three light leptons and a ${\tau _\mathrm {h}}$ (4lI, right). Signal models corresponding to higgsino pair production with scenarios corresponding to decay to HZ (red line, Higgsino mass of 150 GeV), and HH (green line, Higgsino mass of 150 GeV) are shown superimposed. |
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Figure 16-b:
Observed and expected yields across the search regions in events with four light leptons not forming two OSSF pairs (4lH, left), and in events with three light leptons and a ${\tau _\mathrm {h}}$ (4lI, right). Signal models corresponding to higgsino pair production with scenarios corresponding to decay to HZ (red line, Higgsino mass of 150 GeV), and HH (green line, Higgsino mass of 150 GeV) are shown superimposed. |
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Figure 17:
Observed and expected yields across the search regions in events with two light leptons and two ${\tau _\mathrm {h}}$, forming two OSSF pairs (4lJ, left), and forming one or less OSSF pairs (4lK, right). Signal models corresponding to higgsino pair production with scenarios corresponding to decay to HZ (red line, Higgsino mass of 150 GeV), and HH (green line, Higgsino mass of 150 GeV) are shown superimposed. |
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Figure 17-a:
Observed and expected yields across the search regions in events with two light leptons and two ${\tau _\mathrm {h}}$, forming two OSSF pairs (4lJ, left), and forming one or less OSSF pairs (4lK, right). Signal models corresponding to higgsino pair production with scenarios corresponding to decay to HZ (red line, Higgsino mass of 150 GeV), and HH (green line, Higgsino mass of 150 GeV) are shown superimposed. |
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Figure 17-b:
Observed and expected yields across the search regions in events with two light leptons and two ${\tau _\mathrm {h}}$, forming two OSSF pairs (4lJ, left), and forming one or less OSSF pairs (4lK, right). Signal models corresponding to higgsino pair production with scenarios corresponding to decay to HZ (red line, Higgsino mass of 150 GeV), and HH (green line, Higgsino mass of 150 GeV) are shown superimposed. |
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Figure 18:
Expected test statistic distribution for a background only fit compared to the observed test statistic value, drawn as black dots, for the search regions in each event category. The grey shaded area represents the probability density of the expected test statistic distribution, with 68% and 95% expected ranges respectively drawn in green and orange. |
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Figure 19:
Expected test statistic distribution for a background only fit compared to the observed test statistic value, drawn as black dots, for the neural network targeting WZ mediated superpartner decays at each ${\delta M}$ evaluation. The grey shaded area represents the probability density of the expected test statistic distribution, with 68% and 95% expected ranges respectively drawn in green and orange. |
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Figure 20:
Interpretation of the results for ${\tilde{\chi}^{\pm}_1} {\tilde{\chi}^0_2}$ production with flavor-democratic slepton mediated decays, and the parameter governing the mass splittings being $x=$ 0.05 (upper left), $x=$ 0.5 (upper right) and $x=$ 0.95 (bottom). The shading in the $m_{{\tilde{\chi}^0_1}}$ versus $m_{{\tilde{\chi}^0_2}}$ plane indicates the 95% CL upper limit on the ${\tilde{\chi}^{\pm}_1} {\tilde{\chi}^0_2}$ production cross section. The contours delineate the mass regions excluded at 95% CL when assuming cross section computed at NLO plus NLL. The observed, observed $\pm $1$\sigma _{\text {theory}}$ ($\pm $1 standard deviation of the theoretical cross sections), median expected, and expected $\pm $1$\sigma _{\text {experiment}}$ bounds obtained with the neural network strategy are shown in black and red. The median expected bound obtained with the search region strategy is shown in blue. The observed limits obtained in the CMS analysis using 35.9 fb$^{-1}$ of data [20] are shown in green. |
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Figure 20-a:
Interpretation of the results for ${\tilde{\chi}^{\pm}_1} {\tilde{\chi}^0_2}$ production with flavor-democratic slepton mediated decays, and the parameter governing the mass splittings being $x=$ 0.05 (upper left), $x=$ 0.5 (upper right) and $x=$ 0.95 (bottom). The shading in the $m_{{\tilde{\chi}^0_1}}$ versus $m_{{\tilde{\chi}^0_2}}$ plane indicates the 95% CL upper limit on the ${\tilde{\chi}^{\pm}_1} {\tilde{\chi}^0_2}$ production cross section. The contours delineate the mass regions excluded at 95% CL when assuming cross section computed at NLO plus NLL. The observed, observed $\pm $1$\sigma _{\text {theory}}$ ($\pm $1 standard deviation of the theoretical cross sections), median expected, and expected $\pm $1$\sigma _{\text {experiment}}$ bounds obtained with the neural network strategy are shown in black and red. The median expected bound obtained with the search region strategy is shown in blue. The observed limits obtained in the CMS analysis using 35.9 fb$^{-1}$ of data [20] are shown in green. |
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Figure 20-b:
Interpretation of the results for ${\tilde{\chi}^{\pm}_1} {\tilde{\chi}^0_2}$ production with flavor-democratic slepton mediated decays, and the parameter governing the mass splittings being $x=$ 0.05 (upper left), $x=$ 0.5 (upper right) and $x=$ 0.95 (bottom). The shading in the $m_{{\tilde{\chi}^0_1}}$ versus $m_{{\tilde{\chi}^0_2}}$ plane indicates the 95% CL upper limit on the ${\tilde{\chi}^{\pm}_1} {\tilde{\chi}^0_2}$ production cross section. The contours delineate the mass regions excluded at 95% CL when assuming cross section computed at NLO plus NLL. The observed, observed $\pm $1$\sigma _{\text {theory}}$ ($\pm $1 standard deviation of the theoretical cross sections), median expected, and expected $\pm $1$\sigma _{\text {experiment}}$ bounds obtained with the neural network strategy are shown in black and red. The median expected bound obtained with the search region strategy is shown in blue. The observed limits obtained in the CMS analysis using 35.9 fb$^{-1}$ of data [20] are shown in green. |
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Figure 20-c:
Interpretation of the results for ${\tilde{\chi}^{\pm}_1} {\tilde{\chi}^0_2}$ production with flavor-democratic slepton mediated decays, and the parameter governing the mass splittings being $x=$ 0.05 (upper left), $x=$ 0.5 (upper right) and $x=$ 0.95 (bottom). The shading in the $m_{{\tilde{\chi}^0_1}}$ versus $m_{{\tilde{\chi}^0_2}}$ plane indicates the 95% CL upper limit on the ${\tilde{\chi}^{\pm}_1} {\tilde{\chi}^0_2}$ production cross section. The contours delineate the mass regions excluded at 95% CL when assuming cross section computed at NLO plus NLL. The observed, observed $\pm $1$\sigma _{\text {theory}}$ ($\pm $1 standard deviation of the theoretical cross sections), median expected, and expected $\pm $1$\sigma _{\text {experiment}}$ bounds obtained with the neural network strategy are shown in black and red. The median expected bound obtained with the search region strategy is shown in blue. The observed limits obtained in the CMS analysis using 35.9 fb$^{-1}$ of data [20] are shown in green. |
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Figure 21:
Interpretation of the results for ${\tilde{\chi}^{\pm}_1} {\tilde{\chi}^0_2}$ production with $\tau $-enriched slepton mediated decays, and the parameter governing the mass splittings being $x=$ 0.05 (upper left), $x=$ 0.5 (upper right) and $x=$ 0.95 (bottom). The contents of the plot are as described in the caption of Fig. yyyyy. |
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Figure 21-a:
Interpretation of the results for ${\tilde{\chi}^{\pm}_1} {\tilde{\chi}^0_2}$ production with $\tau $-enriched slepton mediated decays, and the parameter governing the mass splittings being $x=$ 0.05 (upper left), $x=$ 0.5 (upper right) and $x=$ 0.95 (bottom). The contents of the plot are as described in the caption of Fig. yyyyy. |
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Figure 21-b:
Interpretation of the results for ${\tilde{\chi}^{\pm}_1} {\tilde{\chi}^0_2}$ production with $\tau $-enriched slepton mediated decays, and the parameter governing the mass splittings being $x=$ 0.05 (upper left), $x=$ 0.5 (upper right) and $x=$ 0.95 (bottom). The contents of the plot are as described in the caption of Fig. yyyyy. |
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Figure 21-c:
Interpretation of the results for ${\tilde{\chi}^{\pm}_1} {\tilde{\chi}^0_2}$ production with $\tau $-enriched slepton mediated decays, and the parameter governing the mass splittings being $x=$ 0.05 (upper left), $x=$ 0.5 (upper right) and $x=$ 0.95 (bottom). The contents of the plot are as described in the caption of Fig. yyyyy. |
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Figure 22:
Interpretation of the results for ${\tilde{\chi}^{\pm}_1} {\tilde{\chi}^0_2}$ production with $\tau $-dominated slepton mediated decays, and the parameter governing the mass splittings being $x=$ 0.05 (upper left), $x=$ 0.5 (upper right) and $x=$ 0.95 (bottom). The contents of the plot are as described in the caption of Fig. yyyyy. |
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Figure 22-a:
Interpretation of the results for ${\tilde{\chi}^{\pm}_1} {\tilde{\chi}^0_2}$ production with $\tau $-dominated slepton mediated decays, and the parameter governing the mass splittings being $x=$ 0.05 (upper left), $x=$ 0.5 (upper right) and $x=$ 0.95 (bottom). The contents of the plot are as described in the caption of Fig. yyyyy. |
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Figure 22-b:
Interpretation of the results for ${\tilde{\chi}^{\pm}_1} {\tilde{\chi}^0_2}$ production with $\tau $-dominated slepton mediated decays, and the parameter governing the mass splittings being $x=$ 0.05 (upper left), $x=$ 0.5 (upper right) and $x=$ 0.95 (bottom). The contents of the plot are as described in the caption of Fig. yyyyy. |
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Figure 22-c:
Interpretation of the results for ${\tilde{\chi}^{\pm}_1} {\tilde{\chi}^0_2}$ production with $\tau $-dominated slepton mediated decays, and the parameter governing the mass splittings being $x=$ 0.05 (upper left), $x=$ 0.5 (upper right) and $x=$ 0.95 (bottom). The contents of the plot are as described in the caption of Fig. yyyyy. |
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Figure 23:
Interpretation of the results for ${\tilde{\chi}^{\pm}_1} {\tilde{\chi}^0_2}$ production with WZ mediated decays. The contents of the plot are as described in the caption of Fig. yyyyy. |
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Figure 24:
Interpretation of the results for ${\tilde{\chi}^{\pm}_1} {\tilde{\chi}^0_2}$ production with WH mediated decays. The contents of the plot are as described in the caption of Fig. yyyyy. |
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Figure 25:
Interpretation of the results for ${\tilde{\chi}^0_1}$ pair production, with ZZ mediated decays (upper), HZ mediated decays (middle), and HH mediated decays (bottom). The median expected upper limits (black line) are shown along with the $\pm $1$\sigma $ (0.16 and 0.84 quantiles, green) and $\pm$2$\sigma $ (0.05 and 0.95 quantiles, yellow) bands. |
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Figure 25-a:
Interpretation of the results for ${\tilde{\chi}^0_1}$ pair production, with ZZ mediated decays (upper), HZ mediated decays (middle), and HH mediated decays (bottom). The median expected upper limits (black line) are shown along with the $\pm $1$\sigma $ (0.16 and 0.84 quantiles, green) and $\pm$2$\sigma $ (0.05 and 0.95 quantiles, yellow) bands. |
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Figure 25-b:
Interpretation of the results for ${\tilde{\chi}^0_1}$ pair production, with ZZ mediated decays (upper), HZ mediated decays (middle), and HH mediated decays (bottom). The median expected upper limits (black line) are shown along with the $\pm $1$\sigma $ (0.16 and 0.84 quantiles, green) and $\pm$2$\sigma $ (0.05 and 0.95 quantiles, yellow) bands. |
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Figure 25-c:
Interpretation of the results for ${\tilde{\chi}^0_1}$ pair production, with ZZ mediated decays (upper), HZ mediated decays (middle), and HH mediated decays (bottom). The median expected upper limits (black line) are shown along with the $\pm $1$\sigma $ (0.16 and 0.84 quantiles, green) and $\pm$2$\sigma $ (0.05 and 0.95 quantiles, yellow) bands. |
| Tables | |
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Table 1:
Brief description of the categories used to classify events in the search. |
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Table 2:
Definition of the search regions used for events with two same-sign light leptons. The symbols (++) and (- -) represent requirements on the charge of the leptons. |
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Table 3:
Definition of the search regions used for events with three light leptons at least two of which form an OSSF pair, excluding those with $75 GeV < {M_{\ell \ell}} < $ 105 GeV. |
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Table 4:
Definition of the search regions used for events with three light leptons at least two of which form an OSSF pair, and which satisfy $75 GeV < {M_{\ell \ell}} < $ 105 GeV. |
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Table 5:
Definition of the search regions used for events with three light leptons, none of which form an OSSF pair. |
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Table 6:
Definition of the search regions for events with a $\mu ^{+}\mu ^{-}$ or $e^{+}e^{-}$ pair and an additional ${\tau _\mathrm {h}}$. |
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Table 7:
Definition of the search regions for events with a $e^{\pm}\mu ^{\mp}$ pair and a ${\tau _\mathrm {h}}$. |
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Table 8:
Definition of the search regions for events with a same-sign light lepton pair and a ${\tau _\mathrm {h}}$. |
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Table 9:
Definition of the search regions for events with 2 ${\tau _\mathrm {h}}$ 's and one light lepton. |
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Table 10:
Definition of the search regions for events with 4 light leptons, including 2 separate OSSF pairs |
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Table 11:
Definition of the search regions for events with 4 leptons with one or more ${\tau _\mathrm {h}}$, or without two light lepton OSSF pairs. |
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Table 12:
Systematic uncertainties sources affecting the analysis, with their typical impact on the event yields across the search regions, and the treatment of the correlations across data taking years. Some of the uncertainty sources are treated as uncorrelated across data taking years, while others are treated as correlated. Uncertainties are allowed to vary the normalization of processes across all bins, and in some cases both the normalization and shapes. Uncertainties in the jet energy corrections and b tagging efficiencies are considered separately for signal events which use CMS fast simulation as explained in Section xxxxx, and for the other simulated processes. |
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Table 13:
Summary of the event categories used for the interpretation of the results in terms of different models, and references to the associated figure summarizing the expected and observed 95% CL upper limits. |
| Summary |
|
A search for new physics in events with two lepton of the same charge, or with three or more leptons with up to two hadronically decaying $\tau$ lepton, is presented. A dataset of proton-proton collision with $\sqrt{s} = $ 13 TeV collected by the CMS detector at the LHC, corresponding to an integrated luminosity of 137 fb$^{-1}$ is analyzed. Events are categorized according to the number of leptons, their charges and flavors. Events in each category are further binned using a plethora of kinematic quantities to maximize the sensitivity of the search to an expansive set of hypotheses of supersymmetric particle production via the electroweak interaction. In events with three light leptons, two of which have opposite-sign and same flavor (OSSF), parametric neural networks are used to markedly enhance the sensitivity of the search to several signal hypotheses. No significant deviation from the standard model expectation is observed in any of the event categories, and the null results are interpreted in terms of a number of simplified models of superpartner production. Models of chargino-neutralino pair production with the neutralino forming the lightest supersymmetric particle (LSP), as well as models of effective neutralino pair production with a nearly massless gravitino as the LSP are considered. Exact signal topologies depend on the masses of the leptonic superpartners and the gauge eigenstates mixing into the charginos and neutralinos. If left-handed sleptons lighter than the chargino exist, the chargino-neutralino pair might undergo slepton mediated decays resulting in final states with three leptons. The results of the analysis lead to upper limits of the chargino masses up to 1450 GeV when using a parametric neural network. Searches in events with three light leptons including an OSSF pair provide sensitivity to these models, while events with two same-sign leptons further enhance the sensitivity in experimentally challenging scenarios with small mass differences between charginos and the LSP. If sleptons would be right-handed, the chargino or both the chargino and the neutralino might decay almost exclusively to $\tau$ leptons. In the former scenario chargino masses up to 1150 GeV are excluded, while masses up to 970 GeV are excluded in the latter. Charginos and neutralinos would undergo direct decay to the LSP via the emission of W, Z or Higgs bosons if sleptons are sufficiently heavy. For decays of the chargino-neutralino pair via a W and a Z boson, chargino masses up to 650 GeV are excluded through the usage of a parametric neural network. If the neutralino's decay proceeds via the emission of a Higgs boson, chargino masses up to 300 GeV can be excluded. Models of effective neutralino pair production with an effectively massless gravitino LSP with subsequent decays via Z and Higgs bosons lead to the exclusion of neutralino masses up to 600 GeV. |
| References | ||||
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