Weak scale radiative lepton mass

We construct a ${\mathit{Z}}_8$ 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, and two additional Higgs doublets are introduced to give nearest-neighbor Yukawa couplings. Loop masses are generated when ${\mathit{Z}}_8$ is softly broken down to ${\mathit{Z}}_2$, while ${\mathit{m}}_{\mathit{e}}$ and ${\mathit{m}}_{\mathrm{\mu }}$ generation require Higgs bosons to be weak scale. The ${\mathit{Z}}_2$ symmetry forbids μ→eγ. The most stringent bound comes from τ→μ${\mathrm{\mu }}^{\pm }$ ${\mathit{e}}^{\mp }$. The model has implications for τ→eγ, μe¯→μ¯e conversion, μ→e${\nu }_{\mathit{e}}$ν${\mathrm{¯}}_{\mathrm{\mu }}$, and FCNC decays of E and N (such as E→τ${\mathit{e}}^{\pm }$ ${\mathrm{\mu }}^{\mp }$).