Accidental symmetries in the scalar potential of the Standard Model extended with two Higgs triplets

The two-Higgs-triplet model (2HTM) provides us with an attractive way to simultaneously account for tiny neutrino masses and the observed matter-antimatter asymmetry in our Universe. In this talk, we study the accidental symmetries of the scalar potential in the 2HTM using the bilinear-field formalism. Based on the group-theoretical arguments, we prove that the maximal symmetry group is $\mathrm{S}\mathrm{O}(4)$. We carefully analyze all the subgroups of $\mathrm{S}\mathrm{O}(4)$, and find that there are eight distinct kinds of accidental symmetries in the scalar potential of the 2HTM.