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CMS-PAS-SUS-17-008
Search for resonant production of second generation sleptons with same-sign dimuon events in proton-proton collisions at $\sqrt{s}= $ 13 TeV
Abstract: A search for resonant production of second generation sleptons ($\tilde{\mu}$, $\tilde{\nu}_{\mu}$) via the R-parity-violating coupling $\lambda'_{211}$, in events with two same-sign muons and at least two jets in the final state is presented. While one muon is expected to be produced directly in the slepton decay, the second muon and at least two jets are produced in the subsequent decay of a neutralino or chargino originating from the resonant slepton. The analysis is based on the 2016 dataset of proton-proton collisions at $\sqrt{s}= $ 13 TeV recorded with the CMS detector at the CERN LHC, which corresponds to an integrated luminosity of 35.9 fb$^{-1}$. No significant deviation is observed with respect to standard model expectations. Upper cross section limits are derived in the context of two simplified models representing the dominant signal contributions. The cross section limits are translated into coupling limits for a modified constrained minimal supersymmetric model with $\lambda'_{211}$ as an additional R-parity-violating coupling. The results impose significantly extended restrictions of the parameter space compared to previous searches for similar models.
Figures & Tables Summary References CMS Publications
Figures

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Figure 1:
Dominant signal contributions in a modified cMSSM with $ {{\lambda ^{\prime}_{211}}} $ as an additional coupling. The left and middle diagrams are simulated as simplified models and considered as signal models for this search.

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Figure 2:
Expected (after fit) and observed event yields in the signal regions as defined in Table xxxxx. The grey band shows the systematic uncertainty on the background yields. Also shown are the expected yields for two signal points normalized to their smallest excluded cross section.

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Figure 3:
Expected (after fit) and observed event yields in the $ {\text {M}_{\text {slepton}}} $ and ${\text {M}_{\tilde\chi}}$ distribution. Also shown are the expected yields for two signal points normalized to their smallest excluded cross section.

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Figure 3-a:
Expected (after fit) and observed event yields in the $ {\text {M}_{\text {slepton}}} $ and ${\text {M}_{\tilde\chi}}$ distribution. Also shown are the expected yields for two signal points normalized to their smallest excluded cross section.

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Figure 3-b:
Expected (after fit) and observed event yields in the $ {\text {M}_{\text {slepton}}} $ and ${\text {M}_{\tilde\chi}}$ distribution. Also shown are the expected yields for two signal points normalized to their smallest excluded cross section.

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Figure 4:
Observed upper cross section limits at 95% CL in the mass plane given by $ {\text {m}_{\tilde\chi ^{0}_{1}}} $ and $ {\text {m}_{\tilde\mu}} $ or $ {\text {m}_{\tilde\nu}} $ for sm1 or sm2, respectively. The limit for a specific mass combination is depicted according to the color scale on the right-hand side of the figures.

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Figure 4-a:
Observed upper cross section limits at 95% CL in the mass plane given by $ {\text {m}_{\tilde\chi ^{0}_{1}}} $ and $ {\text {m}_{\tilde\mu}} $ or $ {\text {m}_{\tilde\nu}} $ for sm1 or sm2, respectively. The limit for a specific mass combination is depicted according to the color scale on the right-hand side of the figures.

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Figure 4-b:
Observed upper cross section limits at 95% CL in the mass plane given by $ {\text {m}_{\tilde\chi ^{0}_{1}}} $ and $ {\text {m}_{\tilde\mu}} $ or $ {\text {m}_{\tilde\nu}} $ for sm1 or sm2, respectively. The limit for a specific mass combination is depicted according to the color scale on the right-hand side of the figures.

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Figure 4-c:
Observed upper cross section limits at 95% CL in the mass plane given by $ {\text {m}_{\tilde\chi ^{0}_{1}}} $ and $ {\text {m}_{\tilde\mu}} $ or $ {\text {m}_{\tilde\nu}} $ for sm1 or sm2, respectively. The limit for a specific mass combination is depicted according to the color scale on the right-hand side of the figures.

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Figure 4-d:
Observed upper cross section limits at 95% CL in the mass plane given by $ {\text {m}_{\tilde\chi ^{0}_{1}}} $ and $ {\text {m}_{\tilde\mu}} $ or $ {\text {m}_{\tilde\nu}} $ for sm1 or sm2, respectively. The limit for a specific mass combination is depicted according to the color scale on the right-hand side of the figures.

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Figure 5:
Upper coupling limits as a function of $ {\text {m}_{0}} $ and $ {\text {m}_{1/2}} $ for a modified cMSSM with $ {{\lambda ^{\prime}_{211}}} $ as additional RPV coupling. The color scale at the right side of the figure indicates the coupling limit value for specific parameter combinations. These limits are derived from the upper cross section limits of sm1. For four $ {{\lambda ^{\prime}_{211}}} $ values (0.004, 0.01, 0.02, 0.03), the coupling limits are shown as black contour line.
Tables

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Table 1:
Sources of systematic uncertainties considered in this search and their values and impact ranges in the different signal regions. The background values are given with respect to the processes they concern, while the impacts are normalized to the total event yield in each signal region. For the signal, typical values for the most relevant signal regions are given. The first three blocks affect the backgrounds predictions and list all experimental uncertainties, uncertainties for processes where the yield is obtained from data, and additional uncertainties for simulation based backgrounds. For signal, the first and the last block are relevant.

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Table 2:
Expected and observed event yields in the signal regions. The uncertainties are the total systematic uncertainties on the expected yields. Also shown are the expected yields for two signal points normalized to their smallest excludable cross-section.

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Table 3:
Observed upper coupling limits for the full cMSSM-like model with $ {{\lambda ^{\prime}_{211}}} $ as additional coupling based on sm2 points. The masses and upper limits on the cross sections at 95% CL for the corresponding points are also shown.
Summary
A search for resonant production of second generation sleptons ($\tilde{\mu}$, $\tilde{\nu}_{\mu}$) with 35.9 fb$^{-1}$ of proton-proton collisions recorded in 2016 with the CMS detector has been presented. The search targets resonant slepton production via the RPV coupling $ {{\lambda^{\prime}_{211}}} $ in final states with two same-sign muons and at least two jets in the final state. No significant excess over the background expectation is observed. Upper cross section limits are set in the context of two simplified models covering the dominant production mechanisms in a modified constrained minimal supersymmetric model with $ {{\lambda^{\prime}_{211}}} $ as additional coupling. These exclusion limits are translated into $ {{\lambda^{\prime}_{211}}} $ coupling limits. The results represent the most stringent limits on this particular model of RPV SUSY.
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Compact Muon Solenoid
LHC, CERN