CMS-SUS-17-008

CMS-SUS-17-008 ; CERN-EP-2018-297
Search for resonant production of second-generation sleptons with same-sign dimuon events in proton-proton collisions at $\sqrt{s} = $ 13 TeV
CMS Collaboration
24 November 2018
Eur. Phys. J. C 79 (2019) 305
Abstract: A search is presented for resonant production of second-generation sleptons (${\tilde{\mu}_{\mathrm{L}}} $, $\tilde{\nu}_{\mu}$) via the $R$-parity-violating coupling ${{\lambda^{\prime}_{211}}}$ to quarks, in events with two same-sign muons and at least two jets in the final state. The smuon (muon sneutrino) is expected to decay into a muon and a neutralino (chargino), which will then decay into a second muon and at least two jets. The analysis is based on the 2016 data set of proton-proton collisions at $\sqrt{s} = $ 13 TeV recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. No significant deviation is observed with respect to standard model expectations. Upper limits on cross sections, ranging from 0.00024 to 4.8 pb, are derived in the context of two simplified models representing the dominant signal contributions leading to a same-sign muon pair. The cross section limits are translated into coupling limits for a modified constrained minimal supersymmetric model with ${{\lambda^{\prime}_{211}}}$ as the only nonzero $R$-parity violating coupling. The results significantly extend restrictions of the parameter space compared with previous searches for similar models.
Links: e-print arXiv:1811.09760 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; CADI line (restricted) ;

Figures & Tables	Summary	References	CMS Publications

Additional information on efficiencies needed for reinterpretation of these results are available here.
Additional technical material for CMS speakers can be found here.

Figures
png pdf	Figure 1: Signal contributions from a modified cMSSM with ${{\lambda ^{\prime}_{211}}}$ as an additional coupling, which are considered as simplified signal models SM1 (left) and SM2 (right) in this search. The charge conjugate diagrams are included as well.
png pdf	Figure 1-a: Signal contribution from a modified cMSSM with ${{\lambda ^{\prime}_{211}}}$ as an additional coupling, which is considered as simplified signal model SM1 in this search.
png pdf	Figure 1-b: Signal contribution from a modified cMSSM with ${{\lambda ^{\prime}_{211}}}$ as an additional coupling, which is considered as simplified signal model SM2 in this search.
png pdf	Figure 2: Expected (after fit) and observed event yields in the SR bins as defined in Table 2. The gray band shows the systematic uncertainty in the background yields. Also shown are the expected yields for two signal points normalized to their expected limit on the cross section. The vertical bars denote the Poisson confidence intervals calculated with the Garwood procedure, while the horizontal bars show the bin width.
png pdf	Figure 3: Expected (after fit) and observed event yields in the $ {m(\mu _{1}\mu _{2}+\text {jets})} $ and $ {m(\mu _{2}\text {j}_{1}\text {j}_{2})} $ distribution. Here, $ {m(\mu _{1}\mu _{2}+\text {jets})} $ is defined as the invariant mass of both muons and all jets in the event, and $ {m(\mu _{2}\text {j}_{1}\text {j}_{2})} $ is the invariant mass of the subleading muon and the two leading jets. Also shown are the expected yields for two signal points normalized to their expected limit on the cross section. The vertical bars denote the Poisson confidence intervals calculated with the Garwood procedure, while the horizontal bars show the bin width.
png pdf	Figure 3-a: Expected (after fit) and observed event yields in the $ {m(\mu _{1}\mu _{2}+\text {jets})} $ and $ {m(\mu _{2}\text {j}_{1}\text {j}_{2})} $ distribution. Here, $ {m(\mu _{1}\mu _{2}+\text {jets})} $ is defined as the invariant mass of both muons and all jets in the event. Also shown are the expected yields for two signal points normalized to their expected limit on the cross section. The vertical bars denote the Poisson confidence intervals calculated with the Garwood procedure, while the horizontal bars show the bin width.
png pdf	Figure 3-b: Expected (after fit) and observed event yields in the $ {m(\mu _{1}\mu _{2}+\text {jets})} $ and $ {m(\mu _{2}\text {j}_{1}\text {j}_{2})} $ distribution. Here, $ {m(\mu _{2}\text {j}_{1}\text {j}_{2})} $ is the invariant mass of the subleading muon and the two leading jets. Also shown are the expected yields for two signal points normalized to their expected limit on the cross section. The vertical bars denote the Poisson confidence intervals calculated with the Garwood procedure, while the horizontal bars show the bin width.
png pdf	Figure 4: Observed upper limits on cross sections at 95% CL. The upper left plot shows the limit in the $ {m_{\tilde{\chi}^{0}_{1}}} $ and $ {m_{{\tilde{\mu}}}} $ mass plane for SM1, while the other three plots show the SM2 limits as a function of $ {m_{\tilde{\chi}^{0}_{1}}} $ and $ {m_{{\tilde{\nu}_{\mu}}}} $ for the three different scenarios with $x = $ 0.1 (upper right), $x=$ 0.5 (lower left) and $x=$ 0.9 (lower right). The limit for a specific mass combination is depicted according to the color scale on the right-hand side of the figures.
png pdf	Figure 4-a: Observed upper limits on cross sections at 95% CL. The plot shows the limit in the $ {m_{\tilde{\chi}^{0}_{1}}} $ and $ {m_{{\tilde{\mu}}}} $ mass plane for SM1. The limit for a specific mass combination is depicted according to the color scale on the right-hand side of the figures.
png pdf	Figure 4-b: Observed upper limits on cross sections at 95% CL. The plot shows the SM2 limit as a function of $ {m_{\tilde{\chi}^{0}_{1}}} $ and $ {m_{{\tilde{\nu}_{\mu}}}} $ for the scenario with $x = $ 0.1. The limit for a specific mass combination is depicted according to the color scale on the right-hand side of the figures.
png pdf	Figure 4-c: Observed upper limits on cross sections at 95% CL. The plot shows the SM2 limit as a function of $ {m_{\tilde{\chi}^{0}_{1}}} $ and $ {m_{{\tilde{\nu}_{\mu}}}} $ for the scenario with $x = $ 0.5. The limit for a specific mass combination is depicted according to the color scale on the right-hand side of the figures.
png pdf	Figure 4-d: Observed upper limits on cross sections at 95% CL. The plot shows the SM2 limits as a function of $ {m_{\tilde{\chi}^{0}_{1}}} $ and $ {m_{{\tilde{\nu}_{\mu}}}} $ for the scenario with $x = $ 0.9. The limit for a specific mass combination is depicted according to the color scale on the right-hand side of the figures.
png pdf	Figure 5: Upper limits at 95% CL on the coupling ${{\lambda ^{\prime}_{211}}}$ as a function of ${m_{0}}$ and ${m_{1/2}}$ 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 values of ${{\lambda ^{\prime}_{211}}}$ (0.004, 0.01, 0.02, 0.03), the coupling limits are shown as black contour lines. The dashed lines show the parameters in the model that correspond to the mass of the lightest Higgs boson for three chosen values (124, 125, 126 GeV).

Tables
png pdf	Table 1: Sources of systematic uncertainties considered in this search and the range of yield variations in the signal regions. The background uncertainties are given as fractions of the total background yields in the signal regions. For the signal, the ranges covering the most relevant signal regions for each signal are given. The first three blocks affect the background predictions and list all experimental uncertainties, uncertainties for processes where the yield is obtained from data, and additional uncertainties for simulation-based backgrounds. In the last block, additional uncertainties for the signal prediction are shown.
png pdf	Table 2: Expected and observed event yields in the signal regions. The uncertainties are the total systematic uncertainties in the expected yields. Also shown are the expected yields for two signal points normalized to the expected limits on the cross sections.
png pdf	Table 3: Observed upper limits on cross sections at 95% CL for selected SM2 points. The corresponding limits on ${{\lambda ^{\prime}_{211}}}$ for the modified cMSSM with ${{\lambda ^{\prime}_{211}}}$ as additional coupling are shown as well.

Summary

A search for resonant production of second-generation sleptons (${\tilde{\mu}_{\mathrm{L}}} $, $\tilde{\nu}_{\mu}$) using 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 $R$-parity violating coupling ${{\lambda^{\prime}_{211}}}$ to quarks in final states with two same-sign muons and at least two jets. No significant excess over the background expectation is observed. Upper limits on cross sections are set in the context of two simplified models covering the dominant production mechanisms in a modified constrained minimal supersymmetric model (cMSSM) with ${{\lambda^{\prime}_{211}}}$ as an additional coupling. These limits, ranging from 0.00024 to 4.8 pb, are translated into limits on the coupling ${{\lambda^{\prime}_{211}}}$ in the modified cMSSM, and represent the most stringent limits on this particular model of $R$-parity violating supersymmetry.

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