CCAST, World Lab, Beijing 100080, Peoples R China
; Inst High Energy Phys, Beijing 100049, Peoples R China
With the perturbative QCD approach based on k(T) factorization, we study the pure annihilation type radiative decays B-0 ->phi gamma and B-0 -> J/psi gamma. We find that the branching ratio of B-0 ->phi gamma is (2.7(-0.6-0.6)(+0.3+1.2))x10(-11), which is too small to be measured in the current B factories of BABAR and Belle. The branching ratio of B-0 -> J/psi gamma is (4.5(-0.5-0.6)(+0.6+0.7))x10(-7), which is just at the corner of being observable in the B factories. A larger branching ratio BR(B-s(0)-> J/psi gamma)similar or equal to 5x10(-6) is also predicted. These decay modes will help us in testing the standard model and searching for new physics signals.