Abstract
A search for new long-lived particles decaying to leptons is presented using proton-proton collisions produced by the LHC at √[s]=8 TeV. Data used for the analysis were collected by the CMS detector and correspond to an integrated luminosity of 19.7 fb(-1). Events are selected with an electron and muon with opposite charges that both have transverse impact parameter values between 0.02 and 2 cm. The search has been designed to be sensitive to a wide range of models with nonprompt e-μ final states. Limits are set on the "displaced supersymmetry" model, with pair production of top squarks decaying into an e-μ final state via R-parity-violating interactions. The results are the most restrictive to date on this model, with the most stringent limit being obtained for a top squark lifetime corresponding to cτ=2 cm, excluding masses below 790 GeV at 95% confidence level.
Highlights
The standard model (SM) has been successful at describing the known elementary particles and their interactions, it is considered to be a low-energy effective theory
Since many models of physics beyond the standard model (BSM) predict particles with significant lifetimes [1,2,3,4,5,6,7,8], there have been some dedicated analyses that attempt to identify particles whose production vertices were displaced from the interaction region [9,10,11]
The search described in this Letter is distinct from these analyses in that it does not make any assumptions about the event topology beyond the requirement that the event contain an isolated electron and isolated muon with large impact parameters and opposite charges
Summary
The standard model (SM) has been successful at describing the known elementary particles and their interactions, it is considered to be a low-energy effective theory. In order to be sensitive to a range of BSM particle lifetimes, we conduct this search in three nonoverlapping signal regions (SRn), defined in the 2D space of electron and muon d0. We use cosmic muon events in data and simulation to estimate the degradation of track reconstruction efficiency for large values of the impact parameter [21].
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