A bstract The type II seesaw mechanism for neutrino mass generation usually makes use of one complex scalar triplet. The collider signature of the doubly-charged scalar, the most striking feature of this scenario, consists mostly in decays into same-sign dileptons or same-sign W boson pairs. However, certain scenarios of neutrino mass generation, such as those imposing texture zeros by a symmetry mechanism, require at least two triplets in order to be consistent with the type II seesaw mechanism. We develop a model with two such complex triplets and show that, in such a case, mixing between the triplets can cause the heavier doubly-charged scalar mass eigenstate to decay into a singly-charged scalar and a W boson of the same sign. Considering a large number of benchmark points with different orders of magnitude of the Δ L ?=?2 Yukawa couplings, chosen in agreement with the observed neutrino mass and mixing pattern, we demonstrate that $ H_1^{++}o H_2^{+}{W^{+}} $ can have more than 99?% branching fraction in the cases where the vacuum expectation values of the triplets are small. It is also shown that the above decay allows one to differentiate a two-triplet case at the LHC, through the ratios of events in various multi-lepton channels.
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