Topcolor-assisted technicolor and the decay B-c -> D-s*gamma

Applying the perturbative QCD method, we study the process B-c --> D-s*gamm a in the topcolor-assisted technicolor model (TATCM), and compare the resul ts with those estimated in the standard model (SM). There are two mechanism s which contribute to the B-c --> D-s*gamma process. One proceeds through t he short distance b --> s gamma transition, the other through weak annihila tion accompanied by a photon emission. The contribution of weak annihilatio n is found to be much more important than that of the electromagnetic pengu in in the TATCM, and the branching ratio, BR (Bc --> D-s*gamma), is much sm aller than that in the SM.