The doubly charged scalar: current status and perspectives

The minimal extension of the Standard Model consisting in a doubly charged SU(2)-singlet scalar is theoretically well motivated by a mechanism ofgeneration of the neutrino masses. As this particle allows for lepton flavourviolation, the model is partially constrained by low energy flavour physics.Limits on the mass are also set by direct searches at LHC. Future $e^+e^−$ colliders could have a great sensitivity in exploring the t-channel exchange ofthis particle. Moreover, its resonance production in the single-productionchannel would be possible.