Quarks and Leptons Beyond the Third Generation

Abstract The possibility of additional quarks and leptons beyond the three generations already established is discussed. The make-up of this Report is (1)  Introduction : the motivations for believing that the present litany of elementary fermions is not complete; (2)  quantum numbers : possible assignments for additional fermions; (3)  masses and mixing angles : mass limits from precision electroweak data, vacuum stability and perturbative gauge unification; empirical constraints on mixing angles; (4)  lifetimes and decay modes : their dependence on the mass spectrum and mixing angles of the additional quarks and leptons; the possibility of exceptionally long lifetimes; (5)  dynamical symmetry breaking : the significance of the top quark and other heavy fermions for alternatives to the elementary Higgs Boson; (6)  CP violation : extensions to more generations and how strong CP may be solved by additional quarks; (7)  experimental searches : present status and future prospects; (8)  conclusions .

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