Estimates of long distance contributions to the B_s→γγ decay

Abstract

We present first calculations of new long-distance contributions to B_s→γγ decay due to intermediate D_s and D_s^∗ meson states. The relevant γ vertices are estimated using charge couplings and transition moment couplings. Within our uncertainties, we find that these long-distance contributions could be comparable to the known short-distance contributions. Since they have different Cabibbo-Kobayashi-Maskawa matrix-element factors, there may be an interesting possibility of observing CP violation in this decay.