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Search for long-lived particles decaying into displaced jets in proton-proton collisions at $\sqrt{s}=$ 13 TeV

The collaboration
Phys.Rev. D99 (2019) 032011, 2019

Abstract (data abstract)
A search for long-lived particles decaying into jets is presented. Data were collected with the CMS detector at the LHC from proton-proton collisionsat a center-of-mass energy of 13 $\mathrm{TeV}$ in 2016, corresponding to an integratedluminosity of 35.9 $\mathrm{fb}^{-1}$. The search examines the distinctive topology of displaced tracks and secondary vertices. The selected events are found to be consistent with standard model predictions.For a simplified model in which long-lived neutral particles are pair produced and decay to two jets, pair production cross sections largerthan 0.2 $\mathrm{fb}$ are excluded at $95 \%$ confidence level for a long-lived particle mass larger than 1000 $\mathrm{GeV}$ and proper decay lengths between 3 and 130 $\mathrm{mm}$.Several supersymmetry models with gauge-mediated supersymmetrybreaking or $R$-parity violation, where pair-produced long-lived gluinos or top squarks decay to several final-state topologiescontaining displaced jets, are also tested. For these models, in the mass ranges above 200 $\mathrm{GeV}$, gluino masses up to 2300--2400 $\mathrm{GeV}$ and top squark masses up to 1350--1600 $\mathrm{GeV}$ are excluded for proper decay lengths approximately between 10 and100 $\mathrm{mm}$. These are the most restrictive limits to date on these models.

• #### Figure 1 (top left)

Data from Figure 1, top left

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The distributions of vertex track multiplicity for data, simulated QCD multijet events, and simulated signal events. Data and simulated events...

• #### Figure 1 (top right)

Data from Figure 1, top right

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The distributions of vertex $L_{xy}$ significance for data, simulated QCD multijet events, and simulated signal events. Data and simulated events...

• #### Figure 1 (bottom left)

Data from Figure 1, bottom left

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The distributions of cluster RMS for data, simulated QCD multijet events, and simulated signal events. Data and simulated events are...

• #### Figure 1 (bottom right)

Data from Figure 1, bottom right

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The distributions of likelihood discriminant for data, simulated QCD multijet events, and simulated signal events. Data and simulated events are...

• #### Figure 2 (left)

Data from Figure 2, left

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Numbers of predicted and observed background events for the nominal background method and the three cross-checks in the control region....

• #### Figure 2 (right)

Data from Figure 2, right

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Numbers of predicted and observed background events for the nominal background method and the three cross-checks in the control region....

• #### Figure 3: cross section limits

Data from Figure 3

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The expected and observed $95\%$ $\text{CL}$ upper limits on the pair production cross section of the long-lived particle X, assuming...

• #### Figure 4 (left plot): cross section limits

Data from Figure 4, left

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the expected and observed $95\%$ $\text{CL}$ upper limits on the pair production cross section of the long-lived gluino, assuming a...

• #### Figure 4 (right plot): mass limits

Data from Figure 4, right

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the expected and observed $95\%$ $\text{CL}$ limits for the long-lived gluino model in the mass-lifetime plane, assuming a $100\%$ branching...

• #### Figure 5 (left plot): cross section limits

Data from Figure 5, left

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the expected and observed $95\%$ $\text{CL}$ upper limits on the pair production cross section of the long-lived gluino, assuming a...

• #### Figure 5 (right plot): mass limits

Example location

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the expected and observed $95\%$ $\text{CL}$ limits for the long-lived gluino model in the mass-lifetime plane, assuming a $100\%$ branching...

• #### Figure 6 (left plot): cross section limits

Data from Figure 6, left

10.17182/hepdata.88880.v1/t12

the expected and observed $95\%$ $\text{CL}$ upper limits on the pair production cross section of the long-lived top squark, assuming...

• #### Figure 6 (right plot): mass limits

Data from Figure 6, right

10.17182/hepdata.88880.v1/t13

the expected and observed $95\%$ $\text{CL}$ limits for the long-lived top squark model in the mass-lifetime plane, assuming a $100\%$...

• #### Figure 7 (left plot): cross section limits

Data from Figure 7, left

10.17182/hepdata.88880.v1/t14

the expected and observed $95\%$ $\text{CL}$ upper limits on the the pair production cross section of the long-lived top squark,...

• #### Figure 7 (right plot): mass limits

Data from Figure 7, right

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the expected and observed $95\%$ $\text{CL}$ limits for the long-lived top squark model in the mass-lifetime plane, assuming a $100\%$...

• #### Likelihood ratio for vertex track multiplicity

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The likelihood ratio for vertex track multiplicity

• #### Likelihood ratio for vertex $L_{xy}$ significance

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The likelihood ratio for vertex $L_{xy}$ significance

• #### Likelihood ratio for cluster RMS

The likelihood ratio for cluster RMS, the point where cluster RMS equals $-1.0$ represents the case where there is no...