Same-sign tetralepton signature at the Large Hadron Collider and a future pp collider

We analyze a novel signature of the type-II seesaw model—a same-sign tetralepton signal arising from the mixing of neutral Higgs bosons and their subsequent decays to singly and doubly charged Higgs bosons. For this, we consider wide ranges of the triplet vacuum expectation value (vev) and Yukawa couplings that are consistent with the observed neutrino masses and mixing as well as the LHC search limits. We find that a doubly charged Higgs boson with mass around 250 GeV and triplet vev around 10-4–10-2  GeV can give a significantly large number of events through its decay to same-sign W gauge bosons at the high-luminosity LHC with 3000  fb-1 of data. We also pursue the analysis for a future hadron collider with the c.m. energy of 100 TeV. Considering a heavy Higgs boson of around 900 GeV and an intermediate region of the triplet vev, where both same-sign dilepton and gauge boson decays can occur, we identify a limited range of the parameters where the number of same-sign tetralepton events are as large as 1000.