Search for Doubly Charged Higgs Boson Production in Like-sign Muon Pairs in pp Collisions at √s=7 TeV

A search for doubly charged Higgs boson production at √s = 7 TeV is presented. The data correspond to an integrated luminosity of 1.6 fb−1 collected in 2011 by the ATLAS experiment at the LHC. The search is performed by selecting events with two high momentum muons that have the same electric charge, and by examining the invariant mass distribution of the dimuon pairs. No evidence for resonant production of such dimuon pairs is found, and the pair production cross section of doubly charged Higgs (H±±) bosons times the H±± → μ±μ± branching ratio is constrained to be less than 13 − 1.6 fb for H±± masses between 100 and 400 GeV. For left-right symmetric models, and assuming the Drell-Yan production mechanism and a branching ratio of 100% to dimuon pairs, left-handed H±± bosons are excluded at 95% confidence level for masses less than 375 GeV, while right-handed H±± bosons are excluded below 295 GeV. Assuming a branching ratio of 33% to dimuon pairs, left-handed and right-handed H±± bosons are excluded at 95% confidence level for masses less than 268 GeV and 210 GeV, respectively.