Neutrino mass models at $\mu$TRISTAN

We study the prospects of probing neutrino mass models at the newly proposed antimuon collider $\mu$TRISTAN, involving $\mu^+e^-$ scattering at $\sqrt{s}= 346$ GeV and $\mu^+\mu^+$ scattering at $\sqrt{s}= 2$ TeV. We show that $\mu$TRISTAN is uniquely sensitive to leptophilic neutral and doubly-charged scalars naturally occurring in various neutrino mass models, such as Zee, Zee-Babu, cocktail, and type-II seesaw models, over a wide range of mass and coupling values, well beyond the current experimental constraints. It also allows for the possibility to correlate the collider signals with neutrino mixing parameters and charged lepton flavor violating observables.