Abstract
Abstract A search for anomalous production of events with three or more isolated leptons in pp collisions at $ \sqrt {s} = 7\,TeV $ is presented. The data, corresponding to an integrated luminosity of 4.98 fb−1, were collected by the CMS experiment at the LHC during the 2011 run. The search is applicable to any model of new physics that enhances multiple lepton production. The observed multilepton events are categorized into exclusive search channels based on the identity and kinematics of the objects in the events. An estimate of the standard-model background rates from data is emphasized, but simulation is also used to estimate some of the background rates. The search results are interpreted in the context of supersymmetry, including both R-parity-conserving and R-parity-violating models. We derive exclusion limits as a function of squark, gluino, and chargino masses.
Highlights
Detector and event triggerThe central feature of the CMS apparatus is a superconducting solenoid, of 6 m internal diameter, providing a field of 3.8 T
Background processes and systematic uncertaintiesSeveral SM processes can produce signatures that mimic BSM events with three or more leptons
The rows are labelled by the total number of isolated leptons in the event, the number and mass of opposite-sign same-flavor (OSSF) pairs, and the kinematic conditions; the columns indicate how many of those leptons are τh leptons
Summary
The central feature of the CMS apparatus is a superconducting solenoid, of 6 m internal diameter, providing a field of 3.8 T. Data from pp interactions must satisfy the requirements of a two-level trigger system. The pseudorapidity, η, is a transformation of the polar angle defined by η = − ln(tan(θ/2)) Data for this search are collected with single-electron, double-electron, single-muon, and double-muon triggers, as well as an electron-muon (e-μ) trigger. To ensure that the trigger efficiency is high and stable for our selected events, we require each event selected by the dielectron (dimuon) triggers to have at least one electron (muon) with pT > 20 GeV and another with pT > 10 GeV. Single-lepton-triggered events are required to have either a muon with pT > 35 GeV or an electron with pT > 85 GeV. A single electron (muon) above the pT specified threshold has a trigger efficiency of 94.5% ± 0.7% (87.0% ± 0.5%). The uncertainties in the efficiencies are largely due to the low number of dilepton events in the HT-triggered datasets
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