Search for a doubly-charged boson in four-lepton final states in type II seesaw

CMS and ATLAS have searched for a doubly-charged boson H±±H±± which may arise from type II seesaw in the 7 TeV run at the LHC by considering pair or associated production of doubly-charged bosons under the assumption of degenerate triplet scalars. In this work, we consider non-degenerate triplet components with the mass gap ΔM∼1–40 GeVΔM∼1–40 GeV which leads to enhanced pair-production cross-sections of H±±H±± added by the gauge decays of the heavier neutral and singly-charged bosons. We reevaluate the constraints in the ΔM  –MH++MH++ plane depending on the triplet vacuum expectation value vΔvΔ in the type II seesaw model which are much more stringent than the current search limits. We further study the possibility of observing same-sign tetra-lepton signals in the allowed parameter space which can be probed in the future runs of the LHC.