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 collisions at a center-of-mass energy of 13 TeV in 2016, corresponding to an integrated luminosity of 35.9 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 larger than 0.2 fb are excluded at 95% confidence level for a long-lived particle mass larger than 1000 GeV and proper decay lengths between 3 and 130 mm. Several supersymmetry models with gauge-mediated supersymmetry breaking or $R$-parity violation, where pair-produced long-lived gluinos or top squarks decay to several final-state topologies containing displaced jets, are also tested. For these models, in the mass ranges above 200 GeV, gluino masses up to 2300-2400 GeV and top squark masses up to 1350-1600 GeV are excluded for proper decay lengths approximately between 10 and 100 mm. These are the most restrictive limits to date on these models.
Highlights
A large number of extensions to the standard model (SM) predict the production of long-lived particles at the CERN LHC that can further decay into final states containing jets
The theoretical motivations are extremely rich [1]; examples include split supersymmetry (SUSY) [2,3,4,5,6,7], SUSY with weak R-parity violation (RPV) [8,9,10,11], SUSY with gauge-mediated supersymmetry breaking (GMSB) [12,13,14], “stealth SUSY” [15,16], “Hidden Valley” models [17,18,19], baryogenesis triggered by weakly interacting massive particles (WIMPs) [20,21,22] and twin Higgs models [23,24,25]
Within the solenoid volume are a silicon pixel and strip tracker, a lead tungstate crystal electromagnetic calorimeter (ECAL), and a brass and scintillator hadron calorimeter (HCAL), each composed of a barrel and two endcap detectors
Summary
A large number of extensions to the standard model (SM) predict the production of long-lived particles at the CERN LHC that can further decay into final states containing jets. We search for long-lived particles decaying into jets, with each long-lived particle having a decay vertex displaced from the production vertex by up to 55 cm in the transverse plane. Events used in this analysis were collected with the CMS detector [26] at the LHC from proton-proton (pp) collisions at a center-of-mass energy of 13 TeV in 2016, corresponding to an integrated luminosity of 35.9 fb−1. The search presented in this paper is designed to be sensitive to multiple final-state topologies containing displaced jets, and is sensitive to a wide range of long-lived particle signatures
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