Nanjing Normal Univ, Dept Phys, Jiangsu 210097, Peoples R China
; CCAST, World Lab, Beijing 100080, Peoples R China
; CAS, Inst High Energy Phys, Beijing 100039, Peoples R China
; Beijing Univ, Dept Phys, Beijing 100871, Peoples R China
Within the framework of the top-color-assisted technicolor (TC2) model, we calculate the new physics contributions to the branching ratios B(B-s,B-d-->gammagamma) and CP violating asymmetries r(CP)(-) (B-s,B-d-->gammagamma) in the QCD factorization based on the heavy-quark limit mbmuch greater thanLambda(QCD). Using the considered parameter space, we find that (a) for both B-s-->gammagamma and B-d-->gammagamma decays, the new physics contribution can provide a factor of two to six enhancement to their branching ratios, (b) for the B-s-->gammagamma decay, its direct CP violation is very small in both the SM and TC2 model, and (c) the CP violating asymmetry r(CP)(-) (B-d-->gammagamma) is around the ten percent level in both the SM and TC2 model, but the sign of CP asymmetry in the TC2 model is different from that in the SM.