Flavor conservation and the lepton-quark mass problem

Arguments in favor of the existence of at least one new heavy lepton-quark generation are given, including a heavy neutral lepton. The small (or vanishing) masses of the observed neutrinos are seen as a consequence of a nearly exact (or exact) 'democratic' symmetry in the neutral lepton channel. The (small) masses of the leptons and quarks are related to small righthanded weak currents which lead to flavor changing effects especially for reactions involving the τ-lepton and the t or b quarks. (R.P.) 8 refs