Abstract
A generic search for anomalous production of events with at least three charged leptons is presented. The search uses a pp-collision data sample at a center-of-mass energy of 7 TeV corresponding to 4.6 inverse femtobarns of integrated luminosity collected in 2011 by the ATLAS detector at the CERN Large Hadron Collider. Events are required to contain at least two electrons or muons, while the third lepton may either be an additional electron or muon, or a hadronically decaying tau lepton. Events are categorized by the presence or absence of a reconstructed tau-lepton or Z-boson candidate decaying to leptons. No significant excess above backgrounds expected from Standard Model processes is observed. Results are presented as upper limits on event yields from non-Standard-Model processes producing at least three prompt, isolated leptons, given as functions of lower bounds on several kinematic variables. Fiducial efficiencies for model testing are also provided. The use of the results is illustrated by setting upper limits on the production of doubly-charged Higgs bosons decaying to same-sign lepton pairs.
Highlights
Events with more than two energetic, prompt, and isolated charged leptons are rarely produced at hadron colliders
The bottom panels show the ratio of events observed in data to those expected from background sources for each bin
A generic search for new phenomena in events with at least three energetic, charged, prompt, and isolated leptons has been presented, using a data sample corresponding to an integrated luminosity of 4:6 fbÀ1 of pp collision data collected by the ATLAS experiment
Summary
Events with more than two energetic, prompt, and isolated charged leptons are rarely produced at hadron colliders Such events offer a clean probe of electroweak processes at high center-of-mass energies, and their production at enhanced rates above Standard Model predictions would constitute evidence for new phenomena. Searches for new phenomena at the LHC are challenged by large cross-section Standard Model processes that overwhelm any events from rare interactions. Such backgrounds must be reduced by triggers before storing event data for future study; these triggers should be highly efficient at selecting processes of interest while reducing the overall rate of events by orders of magnitude. IX and are used to set upper limits on the pair production of doubly charged Higgs bosons
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