3RD-FAMILY FLAVOR PHYSICS IN AN SU(3)(3)XSU(2)(L)XU(1)(Y) MODEL

We consider a model in which each family transforms under a different SU(3) color group. The low-energy effective theory is an extension of the standard model, with additional color octet gauge bosons G(H) with mass M that couple preferentially to the third-family quarks. We show that there are two distinct regions of the model's parameter space in which we can simultaneously evade all the current experimental constr aints: one with M approximate to 250 GeV and the other with M greater than or similar to 600 GeV. Within each allowed region, we can obtain a correction to the Zb(b) over bar vertex that is consistent with the slightly high value of R(b) observed at CERN LEP. We show that there a re Delta B = 1 operators in our model that can suppress the B-meson se mileptonic branching ratio B-sl and the charm multiplicity per decay n (c) by enough to reconcile the spectator parton model predictions with the experimental data. In the nonsupersymmetric version of our model we can only obtain the desired corrections to R(b), B-sl, and n(c) in different regions of the allowed parameter space, while in the supersy mmetric version we can obtain all three corrections simultaneously. We also discuss a strong-coupling limit of our model in which the third- family quarks become composite.