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| CMS-PAS-EXO-17-003 | ||
| Search for pair production of second generation leptoquarks at $\sqrt{s}= $ 13 TeV | ||
| CMS Collaboration | ||
| March 2018 | ||
| Abstract: A search for pair production of second-generation leptoquarks is performed using 35.9 fb$^{-1}$ of data collected at $\sqrt{s}= $ 13 TeV in 2016 with the CMS detector at the CERN LHC. Final states with two muons and two jets, or with one muon, two jets, and missing transverse energy are considered. Second-generation leptoquarks with masses less than 1530 GeV (1285 GeV) are excluded for $\beta$=1.0 (0.5), where $\beta$ is the branching fraction of a leptoquark decaying to a charged lepton and a quark. These limits are the most stringent to date on the masses of second-generation leptoquarks. The results of the search are reinterpreted within a long-lived R-parity violating supersymmetry model that also has a final state with two muons and two jets. | ||
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Links:
CDS record (PDF) ;
CADI line (restricted) ;
These preliminary results are superseded in this paper, PRD 99 (2019) 032014. The superseded preliminary plots can be found here. |
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| Figures | |
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Figure 1:
Dominant leading-order diagrams for the pair production of scalar leptoquarks. |
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Figure 1-a:
Dominant leading-order diagram for the pair production of scalar leptoquarks. |
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Figure 1-b:
Dominant leading-order diagram for the pair production of scalar leptoquarks. |
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Figure 1-c:
Dominant leading-order diagram for the pair production of scalar leptoquarks. |
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Figure 1-d:
Dominant leading-order diagram for the pair production of scalar leptoquarks. |
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Figure 1-e:
Dominant leading-order diagram for the pair production of scalar leptoquarks. |
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Figure 2:
Data and background comparison at preselection level for the $ {\mu} {\mu} \mathrm {jj}$ channel, shown for the variables used for final selection cut optimization M$_{{\mu} {\mu}}$ (top), M$_{{\mu} \mathrm {j}}^{\mathrm {min}}$ (bottom left), and S$_{\mathrm {T}}^{{\mu} {\mu} \mathrm {jj}}$ (bottom right). |
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Figure 2-a:
Data and background comparison at preselection level for the $ {\mu} {\mu} \mathrm {jj}$ channel, shown for a variable used for final selection cut optimization, M$_{{\mu} {\mu}}$. |
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Figure 2-b:
Data and background comparison at preselection level for the $ {\mu} {\mu} \mathrm {jj}$ channel, shown for a variable used for final selection cut optimization, M$_{{\mu} \mathrm {j}}^{\mathrm {min}}$. |
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Figure 2-c:
Data and background comparison at preselection level for the $ {\mu} {\mu} \mathrm {jj}$ channel, shown for a variable used for final selection cut optimization, S$_{\mathrm {T}}^{{\mu} {\mu} \mathrm {jj}}$. |
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Figure 3:
Data and background comparison at preselection level for the $ {\mu} {\nu}\mathrm {jj}$ channel, shown for the variables used for final selection cut optimization M$_{\mathrm {T}}^{{\mu} {\nu}}$ (top), M$_{{\mu} \mathrm {j}}$ (bottom left), and S$_{\mathrm {T}}^{{\mu} {\nu}\mathrm {jj}}$ (bottom right). |
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Figure 3-a:
Data and background comparison at preselection level for the $ {\mu} {\nu}\mathrm {jj}$ channel, shown for a variable used for final selection cut optimization, M$_{\mathrm {T}}^{{\mu} {\nu}}$ (top). |
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Figure 3-b:
Data and background comparison at preselection level for the $ {\mu} {\nu}\mathrm {jj}$ channel, shown for a variable used for final selection cut optimization, M$_{{\mu} \mathrm {j}}$. |
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Figure 3-c:
Data and background comparison at preselection level for the $ {\mu} {\nu}\mathrm {jj}$ channel, shown for a variable used for final selection cut optimization, S$_{\mathrm {T}}^{{\mu} {\nu}\mathrm {jj}}$. |
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Figure 4:
Final selection cuts for the three variables for both the $ {\mu} {\mu} \mathrm {jj}$ (left) and $ {\mu} {\nu}\mathrm {jj}$ (right) channels as a function of LQ mass. |
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Figure 4-a:
Final selection cuts for the three variables for the $ {\mu} {\mu} \mathrm {jj}$ channel as a function of LQ mass. |
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Figure 4-b:
Final selection cuts for the three variables for the $ {\mu} {\nu}\mathrm {jj}$ channel as a function of LQ mass. |
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Figure 5:
Data and background event yields at final selection level for the $ \mu \mu \mathrm{jj} $ analysis, as a function of leptoquark mass. 'Other background' includes W+jets and single top. The samples in individual bins are largely overlapping. |
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Figure 6:
Data and background event yields at final selection level for the $ \mu \nu \mathrm{jj} $ analysis, as a function of leptoquark mass. 'Other background' includes Z+jets and single top. The samples in individual bins are largely overlapping. |
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Figure 7:
Data and background comparison at final selection level for $\mathrm {M}_{\mathrm {LQ}}= $ 1400 GeV for the $ {\mu} {\mu} \mathrm {jj}$ (top) and for $\mathrm {M}_{\mathrm {LQ}}= $ 1100 GeV for the $ {\mu} {\nu}\mathrm {jj}$ (bottom) channel, shown for S$_{\mathrm {T}}$ (left) and LQ invariant mass (right). |
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Figure 7-a:
Data and background comparison at final selection level for $\mathrm {M}_{\mathrm {LQ}}= $ 1400 GeV for the $ {\mu} {\mu} \mathrm {jj}$ channel, shown for S$_{\mathrm {T}}$. |
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Figure 7-b:
Data and background comparison at final selection level for $\mathrm {M}_{\mathrm {LQ}}= $ 1400 GeV for the $ {\mu} {\mu} \mathrm {jj}$ channel, shown for LQ invariant mass. |
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Figure 7-c:
Data and background comparison at final selection level for $\mathrm {M}_{\mathrm {LQ}}= $ 1100 GeV for the $ {\mu} {\nu}\mathrm {jj}$ channel, shown for S$_{\mathrm {T}}$. |
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Figure 7-d:
Data and background comparison at final selection level for $\mathrm {M}_{\mathrm {LQ}}= $ 1100 GeV for the $ {\mu} {\nu}\mathrm {jj}$ channel, shown for LQ invariant mass. |
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Figure 8:
The expected and observed upper limits at 95% CL on the leptoquark pair production cross section times $\beta ^2$ ($2\beta (1-\beta)$) as a function of the second-generation leptoquark mass obtained with the $ \mu \mu \mathrm{jj} $ (left) and $ \mu \nu \mathrm{jj} $ (right) analysis. The solid lines represent the observed limits, the dashed lines represent the median expected limits, and the colored bands represent the 68% and 95% confidence intervals. The $\sigma _{\rm theory}$ curves and their bands represent, respectively, the theoretical scalar leptoquark pair production cross section and the uncertainties due to the choice of PDF and renormalization/factorization scales. |
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Figure 8-a:
The expected and observed upper limits at 95% CL on the leptoquark pair production cross section times $\beta ^2$ ($2\beta (1-\beta)$) as a function of the second-generation leptoquark mass obtained with the $ \mu \mu \mathrm{jj} $ analysis. The solid lines represent the observed limits, the dashed lines represent the median expected limits, and the colored bands represent the 68% and 95% confidence intervals. The $\sigma _{\rm theory}$ curves and their bands represent, respectively, the theoretical scalar leptoquark pair production cross section and the uncertainties due to the choice of PDF and renormalization/factorization scales. |
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Figure 8-b:
The expected and observed upper limits at 95% CL on the leptoquark pair production cross section times $\beta ^2$ ($2\beta (1-\beta)$) as a function of the second-generation leptoquark mass obtained with the $ \mu \nu \mathrm{jj} $ analysis. The solid lines represent the observed limits, the dashed lines represent the median expected limits, and the colored bands represent the 68% and 95% confidence intervals. The $\sigma _{\rm theory}$ curves and their bands represent, respectively, the theoretical scalar leptoquark pair production cross section and the uncertainties due to the choice of PDF and renormalization/factorization scales. |
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Figure 9:
The expected and observed exclusion limits at 95% CL for second-generation leptoquark mass as a function of the branching fraction $\beta $ vs. LQ mass M$_\mathrm {LQ}$. The dark green and light yellow expected limit uncertainty bands represent the 68% and 95% confidence intervals on the combination. Limits for the individual $ \mu \mu \mathrm{jj} $ and $ \mu \nu \mathrm{jj} $ channels are also given. Solid lines represent the observed limits in each channel, and dashed lines represent the expected limits. |
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Figure 10:
Expected and observed upper limits at 95% CL on the long-lived RPV SUSY $\tilde{t}$ pair production cross section as a function of $\tilde{t}$ mass (x-axis) and lifetime (y-axis). The expected limits and uncertainty bands represent the median expected limits and the 68% and 95% confidence intervals. Extrapolation has been performed to produce a limit plot down to the prompt kinematic range. |
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Figure 11:
Signal acceptance*efficiency for optimized final selections as a function of scalar LQ mass in the $ {\mu} {\mu} \mathrm {jj}$ (left) and $ {\mu} {\nu}\mathrm {jj}$ (right) channels. |
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Figure 11-a:
Signal acceptance*efficiency for optimized final selections as a function of scalar LQ mass in the $ {\mu} {\nu}\mathrm {jj}$ channel. |
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Figure 11-b:
Signal acceptance*efficiency for optimized final selections as a function of scalar LQ mass in the $ {\mu} {\mu} \mathrm {jj}$ channel. |
| Tables | |
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Table 1:
Range of systematic uncertainties on the signal acceptance and background (BG) yields for the $ {\mu} {\mu} \mathrm {jj}$ analysis. The last two lines show the total systematic uncertainty, and the total statistical uncertainty of the simulated samples, respectively. |
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Table 2:
Range of systematic uncertainties on the signal acceptance and background (BG) yields for the $ {\mu} {\nu}\mathrm {jj}$ analysis. The last two lines show the total systematic uncertainty, and the total statistical uncertainty of the simulated samples, respectively. |
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Table 3:
Event yields at final selection level for the $ \mu \mu \mathrm{jj} $ analysis. 'Other BG' includes W+jets and single top. Uncertainties are statistical unless otherwise indicated. |
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Table 4:
Event yields at final selection level for the $ \mu \nu \mathrm{jj} $ analysis. 'Other BG' includes Z+jets and single top.Uncertainties are statistical unless otherwise indicated. |
| Summary |
| A search has been performed for pair production of second-generation leptoquarks using 35.9 fb$^{-1}$ of proton-proton collisions collected at $\sqrt{s}$=13 TeV in 2016 with the CMS detector at the CERN LHC. Limits have been set on pair production in the $ \mu \mu \mathrm{jj} $ ($ \mu \nu \mathrm{jj} $) channels for $\beta$ = 1 (0.5) as a function of leptoquark mass. Two-dimensional limits have also been set in the $\beta$ - leptoquark mass plane. The $ \mu \mu \mathrm{jj} $ search has been reinterpreted in the context of a displaced SUSY model. These limits represent the most stringent limits to date on these models. |
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Compact Muon Solenoid LHC, CERN |
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