  The Standard Model provides an excellent description of the observables
measured at high energy lepton and hadron colliders. However, measurements of
the forward-backward asymmetry of the bottom quark at LEP suggest that the
effective coupling of the right-handed bottom quark to the neutral weak gauge
boson is significantly different from the value predicted by the Standard
Model. Such a large discrepancy may be the result of a mixing of the bottom
quark with heavy mirror fermions with masses of the order of the weak scale. To
be consistent with the precision electroweak data, the minimal extension of the
Standard Model requires the presence of vector-like pairs of SU(2) doublet and
singlet quarks. In this article, we show that such an extension of the Standard
Model is consistent with the unification of gauge couplings and leads to a very
rich phenomenology at the Tevatron, the B-factories and the LHC. In particular,
if the Higgs boson mass lies in the range 120 GeV $\simlt m_h \simlt 180$ GeV,
we show that Run II of the Tevatron collider with 4--8 fb$^{-1}$ of integrated
luminosity will have the potential to discover the heavy quarks, while
observing a 3-$\sigma$ evidence of the Higgs boson in most of the parameter
space. We also discuss the effects on the time dependent CP-asymmetry in $B \to
\phi K_s$ decays.
