Minimal flavor violation in the see-saw portal

We consider an extension of the Standard Model with two singlet leptons, with masses in the electroweak range, that induce neutrino masses via the see-saw mechanism, plus a generic new physics sector at a higher scale, A. We apply the minimal flavor violation (MFV) principle to the corresponding Effective Field Theory (nu SMEFT) valid at energy scales E << A. We identify the irreducible sources of lepton flavor and lepton number violation at the renormalizable level, and apply the MFV ansatz to derive the scaling of the Wilson coefficients of the nu SMEFT operators up to dimension six. We highlight the most important phenomenological consequences of this hypothesis in the rates for exotic Higgs decays, the decay length of the heavy neutrinos, and their production modes at present and future colliders. We also comment on possible astrophysical implications.