Family Structure of Quarks and Leptons

As a partial solution to the mystery of the observed family struc- ture of quarks and leptons, we present a class of models in which the observed K-M mixing angles including the strength of the weak- CP violation are all explained in terms of the observed quark mass eigenvalue ratios. These are the left-right symmetric, CP-invariant, gauge models in which the family symmetry plays the crucial role so that the quark mass matrices are given by the symmetric Fritzsch form with the two fundamental phases which enter the expression for the K-M matrix are both equal to (pi)/2 (or -(pi)/2). Spontaneous symmetry breaking is responsible for the generation of these fundamental phases as well as the observed parity violation in the weak interaction sector. Both of the strong CP and the weak CP are well understood from the family symmetry point of view and the invisibility of the axion is observed to be naturally related to the low energy phenomena such as the observed absence of the F.C.N.C. and the long b-quark lifetime. The key prediction of the models is 5.0 x 10('-3) (LESSTHEQ) R(,b) (TBOND) (GAMMA)(b (--->) ue(nu))/(GAMMA)(b (--->) ce(nu)) (LESSTHEQ) 1.46 x 10('-2), while the present upper bound on R(,b) is R(,b) (LESSTHEQ) 3 x 10('-2). This prediction will be tested by experiments at CLEO and CUSB in the near future.