Rare B{sub (s)} decays in the standard model and in a scenario with two universal extra dimensions

I consider the exclusive B{yields}K*{gamma}, B{yields}K*{sub 2}{gamma}, B{sub s}{yields}{phi}{gamma} and B{yields}K{eta}{sup ( Prime )}{gamma} radiative decays in the Standard Model and in a scenario with two universal extra dimensions compactified on a chiral square. Computed branching fractions depend on 1/R, the size of the extra dimensions, so that comparison with available data allows to put bounds on such a parameter. The most stringent bound comes from the mode B*{sup 0}{yields}K*{sup 0}{gamma} and reads: 1/R > 710 GeV.