Anomalous Wtb Couplings and b→sγin the Topcolor Assisted Technicolor Models

Using the topcolor-assisted technicolor models,we give the anomalous Wtb couplings arising from the exchange of the new gauge bosons(ETC gauge boson,colorons and Z')and calculate their contributions to the b→sγbranching ratio.We find that the contributions mainly come from colorons and the recent measured value of the b→sγbranching ratio gives a strong constraint on the masses of colorons.