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Search for long-lived particles using nonprompt jets and missing transverse momentum with proton-proton collisions at $\sqrt{s} =$ 13 TeV

The collaboration
Phys.Lett. B797 (2019) 134876, 2019

Abstract (data abstract)
A search for long-lived particles decaying to displaced, nonprompt jets and missing transverse momentum is presented. The data sample corresponds to an integrated luminosity of 137 $\textrm{fb}^{-1}$ of proton-proton collisions at a center-of-mass energy of 13 TeV collected by the CMS experiment at the CERN LHC in 2016--2018. Candidate signal events containing nonprompt jets are identified using the timing capabilities of the CMS electromagnetic calorimeter. The results of the search are consistent with the background prediction and are interpreted using a gauge-mediated supersymmetry breaking reference model with a gluino next-to-lightest supersymmetric particle. In this model, gluino masses up to 2100, 2500, and 1900 GeV are excluded at $95\%$ confidence level for proper decay lengths of 0.3, 1, and 100 m, respectively. These are the best limits to date for such massive gluinos with proper decay lengths greater than $\sim$0.5 m.

• #### Table 2 (predictions)

Contents of Table 2

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Summary of the estimated number of background events.

• #### Figure 2 (Jet time distributions)

Contents of Figure 2.

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The timing distribution of the background sources predicted to contribute to the signal region, compared to those for a representative...

• #### Figure 3 (2D effs)

Contents of Figure 3.

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The product of the acceptance and efficiency in the $c\tau_{0}$ vs. $m_{\tilde{g}}$ plane for the GMSB model, after all requirements.

• #### Figure 4 (2D obs limits)

Contents of Figure 4.

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The observed upper limits at $95\%$ CL for the gluino pair production cross section in the GMSB model, shown in...

• #### Figure 4 (Contours)

Contents of Figure 4.

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The observed upper limits at $95\%$ CL for the gluino pair production cross section in the GMSB model, shown in...

• #### Figure 5 (limits for $m_\tilde{g} = 2400$ GeV)

Contents of Figure 5.

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The observed and expected upper limits at $95\%$ CL on the gluino pair production cross section for a gluino GMSB...

• #### Additional Figure 1

Contents of Additional Figure 1.

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The distribution (normalized to unity) of number of ECAL cells hit in the jet for jets in a background enriched...

• #### Additional Figure 2

Contents of Additional Figure 2.

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• #### Additional Figure 4

Contents of Additional Figure 4.

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• #### Additional Figure 6

Contents of Additional Figure 6.

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The distribution (normalized to unity) of $p_\mathrm{T}tf$ for a data sample enriched in main bunch backgrounds (satisfying $p_\mathrm{T} > 30\,\mathrm{GeV}$,...

• #### Additional Figure 7

Contents of Additional Figure 7.

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• #### Additional Figure 23 (2D timing)

Contents of Additional Figure 23.

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Contribution to the delayed time of jets from the $\beta$ of the gluino is plotted against the delay contribution from...

• #### Additional Table 1 (cutflow $m_{\tilde{g}}=1000$)

Contents of Additional Table 1

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Selection efficiencies for the GMSB model with $m_{\tilde{g}}=1000$ and various proper decay lengths

• #### Additional Table 2 (cutflow $m_{\tilde{g}}=2400$)

Contents of Additional Table 2

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Selection efficiencies for the GMSB model with $m_{\tilde{g}}=2400$ and various proper decay lengths

• #### Additional Table 3 (cutflow $m_{\tilde{g}}=3000$)

Contents of Additional Table 3

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Selection efficiencies for the GMSB model with $m_{\tilde{g}}=3000$ and various proper decay lengths

• #### Additional Figure 24 (2D limits)

Contents of Additional Figure 24.

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The observed upper limits at $95\%$ CL for the gluino pair production cross section relative to the theoretical cross section...

• #### Additional Figure 25 (2D limits)

Contents of Additional Figure 25.

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The expected upper limits at $95\%$ CL for the gluino pair production cross section relative to the theoretical cross section...

• #### Additional Figure 26 (2D limits)

Contents of Additional Figure 26.

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The expected plus 1 $\sigma_{\mathrm{experiment}}$ upper limits at $95\%$ CL for the gluino pair production cross section relative to the...

• #### Additional Figure 27 (2D limits)

Contents of Additional Figure 27.

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The expected minus 1 $\sigma_{\mathrm{experiment}}$ upper limits at $95\%$ CL for the gluino pair production cross section relative to the...

• #### Additional Figure 28 (2D limits)

Contents of Additional Figure 28.

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The expected upper limits at $95\%$ CL for the gluino pair production cross section in the GMSB model, shown in...

• #### Additional Figure 29 (2D limits)

Contents of Additional Figure 29.

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The expected plus 1 $\sigma_{\mathrm{experiment}}$ upper limits at $95\%$ CL for the gluino pair production cross section in the GMSB...

• #### Additional Figure 30 (2D limits)

Contents of Additional Figure 30.

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The expected minus 1 $\sigma_{\mathrm{experiment}}$ upper limits at $95\%$ CL for the gluino pair production cross section in the GMSB...

Version 2 modifications: Updated signal cross sections to NNLO. Minor aesthetic changes.