Phenomenology of a Higgs triplet model at future $e^{+}e^{-}$ colliders

Abstract

In this work, we investigate the prospects of future $e^{+}e^{-}$ colliders in testing a Higgs triplet model with a scalar triplet and a scalar singlet under $SU(2)$. The parameters of the model are fixed so that the lightest $CP-$even state corresponds to the Higgs particle observed at the LHC at around $125$ GeV. This study investigates if the second heaviest $CP-$even, the heaviest $CP-$odd and the singly charged states can be observed at existing and future colliders by computing their accessible production and decay channels. In general, the LHC is not well equipped to produce a Higgs boson which is not mainly doublet-like, so we turn our focus to lepton colliders. We find distinctive features of this model in cases when the second heaviest $CP-$even Higgs is triplet-like, singlet-like or a mixture. These features could distinguish the model from other scenarios at future $e^{+}e^{-}$ colliders.

29 pages, 14 figures. Changes in v3 includes: a clear motivation in the introduction; further numbers on LHC production; inclusion of gluon and one-loop decays in Tables VIII and IX. Figures 8, 9, 10, 11 and 12 now include the new decays. None of the conclusions of our work change. New section VII summarising potential channels for discovery. Version accepted for publication in Physical Review D