Remarks on the mass scales, mixing angles, and signatures of the fourth-generation quarks

Assuming that the fourth family makes an appreciable contribution to B mixing, assuming some mild properties of the (4×4) Cabibbo-Kobayashi-Maskawa matrix, and taking the lattice determination of the pseudoscalar decay constant for B seriously, we arrive at a lower bound on $m_t$, i.e., $m_{t\mathcal{’}}$≳500 GeV. If perturbative unitarity is to be preserved, i.e., $m_{t\mathcal{’}}$∼500 GeV, then our analysis also implies that the top quark is unlikely to be lighter than ≊80 Gev. Experimental consequences for rare B decays, and CP violation in B decays are also discussed.