Contemplating the Possible Number of Quark-Lepton Generations
Ziro Maki · Progress of Theoretical Physics Supplement · 1986
The problem of mysterious repetition of quark-lepton families is briefly reviewed according to different conceptions on the fundamental constituents of matter. We argue that the bound of number of generations, if exists, might be guessed closely relating with a limit of validity of physical concept of quarks and leptons as the low-energy effective fields. We expect with certain phenomenological grounds the number of generations of low-lying quarks-leptons is most probably limited to be five.