In this paper we calculate some rare decays of heavy quarks (b and t) using the ideas of technivector meson dominance and TC spectral functions. The low energy ETC dynamics that gives rise to the large mass of the top quark inevitably induces such FCNC decays of b and t quarks. We find that in an SU(4${)}_{\mathrm{TC}}$ model with 1 and 10 doublets of technifermions the b→sγ decay rate, for ${\mathit{m}}_{\mathit{t}}$≊150 GeV, will be modified by 11% and 26%, respectively, from the SM value, whereas for the same top mass the branching ratios for the rare decays t→cγ and t→cZ get contributions ∼${10}^{\mathrm{-}10}$–${10}^{\mathrm{-}9}$ and ∼${10}^{\mathrm{-}6}$ from the ordinary TC scenario. These values are greater than the corresponding SM predictions by 2–3 and 7 orders of magnitude, respectively. In particular, for TC models the rare decay t→cZ has a good prospect of being observed at the CERN LHC. The SSC, which has recently been abandoned, would also have produced an observable number of such decays.

• Received 21 April 1994

DOI:https://doi.org/10.1103/PhysRevD.51.6221