B_{s,d}\to \gamma\gamma decay in the model with one universal extra   dimension
  We estimate the beyond the Standard Model (SM) contribution to the B_{s,d} \to \gamma\gamma double radiative decay in the framework of the model with one universal extra dimension. This contribution gives a \sim 3 (6)% enhancement of the branching ratio calculated in the SM for B_{s (d)} \to \gamma\gamma. 
G. Devidze, A. Liparteliani, Ulf-G. Mei{\ss}ner