Search for Anomalous Production of Prompt Like-Sign Lepton Pairs at $\sqrt{s}=7$~TeV with the ATLAS Detector

An inclusive search for anomalous production of two prompt, isolated leptons with the same electric charge is presented. The search is performed in a data sample corresponding to 4.7 $\mathrm{fb}^{-1}$ of integrated luminosity collected in 2011 at $\sqrt{s}=7$ TeV with the ATLAS detector at the LHC. Pairs of high-$p_{T}$ leptons ($e^{\pm}e^{\pm}$, $e^{\pm}\mu^{\pm}$, and $\mu^{\pm}\mu^{\pm}$) are selected, and the dilepton invariant mass distribution is examined for any deviation from the Standard Model expectation. No excess is found, and upper limits on the production of like-sign lepton pairs due to contributions from physics beyond the Standard Model are placed as a function of the dilepton mass within a fiducial region close to the experimental selection criteria. The 95% confidence level upper limits on the cross section of anomalous $e^{\pm}e^{\pm}$, $e^{\pm}\mu^{\pm}$, or $\mu^{\pm}\mu^{\pm}$ production range between 1.7 fb and 64.1 fb depending on the dilepton mass and flavor combination. The same data are interpreted in the context of a search for a narrow doubly-charged resonance, using the doubly-charged Higgs boson as a benchmark model. The masses of doubly-charged Higgs bosons are constrained depending on the branching ratio into these leptonic final states. Assuming pair production, coupling to left-handed fermions, and a branching ratio of 100% for each final state, masses below 409 GeV, 375 GeV, and 398 GeV are excluded for $e^{\pm}e^{\pm}$, $e^{\pm}\mu^{\pm}$, and $\mu^{\pm}\mu^{\pm}$, respectively.