A Model of Strong Flavor Dynamics for the Top Quark
  We discuss a model in which the third generation fermions undergo a different $SU(2)$ weak interaction from the first two generation fermions. In general, a flavor changing neutral current interaction is expected. Constrained by the precision low energy data, the mass ($M_{Z'}=M_{W'}$) of the heavy gauge bosons is bounded from below to be about $1.1$ TeV for $\alpha_s=0.125$ and about $1.3$ TeV for $\alpha_s=0.115$, at the $3\sigma$ level. This model favors a larger $R_b$ and a smaller $R_c$ as compared with the Standard Model, but it does not explain the $R_c$ data. If one takes the $R_b$ data seriously, then $M_{Z'}$ is bounded, at the $3\sigma$ level, to be $462$ GeV $< M_{Z^{\prime}} \cos\phi < 1481\,\, {\rm{GeV}}$, where $\cos\phi$ is the mixing angle between the two $SU(2)$'s in the model. Effects predicted for high energy experiments at the Tevatron, LEP140, LEP-II, LHC, and future linear colliders are also discussed. 
Ehab Malkawi, Tim Tait, and C.--P. Yuan