One-loop-induced fermion masses and exotic interactions in a standard-model context

The standard SU(2)×{}U(1) electroweak gauge model is extended to include a fourth generation of quarks and leptons as well as four extra Higgs-boson doublets. With the implementation of a Z₄ discrete symmetry, which is softly broken down to Z₂, realistic radiative quark and lepton masses for the first two generations can be obtained. Assuming that the third and fourth lepton generations are odd under the unbroken Z₂, we discuss a number of interesting phenomenological consequences such as a longer τ lifetime and some possible anomalous τ interactions. We also single out some processes involving fourth-generation quarks and leptons which cannot be confused experimentally with those of the standard model.