Search for Displaced Supersymmetry in events with an electron and a muon with large impact parameters

TL;DR

This paper reports a search for long-lived particles decaying into electron-muon pairs with large impact parameters, setting new limits on displaced supersymmetry models using LHC data.

Contribution

It introduces a novel search strategy for displaced supersymmetry with nonprompt e-mu final states and provides the most restrictive limits to date on top squark masses and lifetimes.

Findings

Excluded top squark masses below 790 GeV for c tau = 2 cm

Set the most stringent limits on displaced supersymmetry models

Sensitive to a wide range of nonprompt lepton final states

Abstract

A search for new long-lived particles decaying to leptons is presented using proton-proton collisions produced by the LHC at sqrt(s) = 8 TeV. Data used for the analysis were collected by the CMS detector and correspond to an integrated luminosity of 19.7 inverse femtobarns. Events are selected with an electron and a muon that have transverse impact parameter values between 0.02 cm and 2 cm. The search has been designed to be sensitive to a wide range of models with nonprompt e-mu final states. Limits are set on the "displaced supersymmetry" model, with pair production of top squarks decaying into an e-mu 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 c tau = 2 cm, excluding masses below 790 GeV at 95% confidence level.