Radiative Lepton Masses with Heavy Lepton Seed

We construct a Z8 model for leptons where all Yukawa couplings are of order unity, but known lepton masses are generated radiatively, order by order. The seed is provided by fourth generation leptons E and N , which receive (Dirac) mass in usual way. Two additional Higgs doublets with nontrivial Z8 charge are introduced to give nearest neighbor Yukawa couplings. Hence, nonstandard Higgs bosons are flavor changing in an unusual way. Loop masses are generated when Z8 is softly broken down to Z2. However, e and μ mass generation require new Higgs bosons to be at weak scale. Neutral scalar mixing underlies mμ/mτ ≫ me/mμ, mτ/mE . The Z2 symmetry forbids μ → eγ and τ → μγ. The most stringent bound comes from τ → μμe. The model has interesting implications for τ → eγ, μē → μ̄e conversion, μ → eνeν̄μ, and FCNC decays of E and N (such as E → τeμ).