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CMS-PAS-EXO-16-036
Search for heavy stable charged particles with 12.9 fb$^{-1}$ of 2016 data
Abstract: Results from searches for heavy, stable, charged particles are presented using data from pp collisions at a center-of-mass energy of 13 TeV using 12.9 fb$^{-1}$ data from 2016 LHC operations. The distinctive signatures of large $dE/dx$ and long time-of-flight are used to discriminate signal from background using the CMS detector. The data are consistent with expected background. Upper limits are set on the cross section for production of long-lived gluinos, scalar tops, scalar taus, and lepton-like fermions. In addition, lower mass limits are set for these signals. The mass limit on gluinos is found to be 1850 GeV.
Figures & Tables Summary References CMS Publications
Figures

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Figure 1-a:
Observed and predicted mass spectra for candidates entering the tracker-only (a) and tracker+TOF (b) signal region for the loose selection. The expected distribution for a representative signal is shown in green.

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Figure 1-b:
Observed and predicted mass spectra for candidates entering the tracker-only (a) and tracker+TOF (b) signal region for the loose selection. The expected distribution for a representative signal is shown in green.

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Figure 2-a:
Observed and predicted mass spectra for candidates entering the tracker-only (a) or tracker+TOF (b) signal region for the final selection. The expected distribution for a representative signal is shown in green.

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Figure 2-b:
Observed and predicted mass spectra for candidates entering the tracker-only (a) or tracker+TOF (b) signal region for the final selection. The expected distribution for a representative signal is shown in green.

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Figure 3-a:
Cross section upper limits at 95% CL on various signal models for the tracker-only analysis (a) and tracker+TOF analysis (b) at $\sqrt {s} = $ 13 TeV . In the legend, 'CS' stands for charged suppressed interaction model.

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Figure 3-b:
Cross section upper limits at 95% CL on various signal models for the tracker-only analysis (a) and tracker+TOF analysis (b) at $\sqrt {s} = $ 13 TeV . In the legend, 'CS' stands for charged suppressed interaction model.
Tables

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Table 1:
Selection criteria for the various subanalyses with the number of predicted and observed events.

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Table 2:
Systematic uncertainties for the various HSCP searches. All values are relative uncertainties. The middle columns show the range of values while the last two columns show two example cases: gluino ($f=$ 0.1, $M =$ 1800 GeV) and GMSB stau ($M =$ 651 GeV).

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Table 3:
Summary of the $p_{T}$, $I_{as}$, $1/\beta $, and mass thresholds, the observed and predicted yields passing these criteria, and the resulting expected (Exp.) and observed (Obs.) cross section limits for gluino signals. The signal efficiency and theoretical (Th.) cross section are also listed.

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Table 4:
Summary of the $p_{T}$, $I_{as}$, $1/\beta $, and mass thresholds, the observed and predicted yields passing these criteria, and the resulting expected (Exp.) and observed (Obs.) cross section limits for stop signals. The signal efficiency and theoretical (Th.) cross section are also listed.

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Table 5:
Summary of the $p_{T}$, $I_{as}$, $1/\beta $, and mass thresholds, the observed and predicted yields passing these criteria, and the resulting expected (Exp.) and observed (Obs.) cross section limits for stau signals. The signal efficiency and theoretical (Th.) cross section are also listed.

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Table 6:
Summary of the $p_{T}$, $I_{as}$, $1/\beta $, and mass thresholds, the observed and predicted yields passing these criteria, and the resulting expected (Exp.) and observed (Obs.) cross section limits for modified Drell-Yan models of various charge signals. The signal efficiency and theoretical (Th.) cross section are also listed.

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Table 7:
Mass limits obtained using 2016 data for various HSCP candidate models. The expected mass limits are shown in parenthesis. In the model name, 'CS' stands for charged suppressed interaction model.
Summary
A number of searches for heavy stable charged particles produced in proton-proton collisions at $\sqrt{s} = $ 13 TeV using the CMS detector are presented. Two complementary analyses were performed: a search using only the tracker and a search using both the tracker and the muon system. Data are found to be compatible with the background expectation. Mass limits for gluinos, stops, staus, and multiply charged particles are calculated. The models for $R$-hadron-like HSCPs include varying the fraction of $\tilde{g}-$gluon production and two different interaction models producing a variety of exotic experimental signatures. The limits, ranging up to 1850 GeV for gluinos, represent significant improvements on previous limits from the LHC.
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