Rare B decays in a single Universal Extra Dimension scenario

Exclusive rare $B \to K^{(*)} \ell^+ \ell^-$, $B \to K^{(*)} \nu \bar \nu$ and $B \to K^* \gamma$ decays are studied within the Applequist-Cheng-Dobrescu model, an extension of the Standard Model in presence of universal extra dimensions. In the case of a single universal extra dimension compactified on a circle of radius R, we study the dependence of several observables on 1/R, and discuss whether the hadronic uncertainty due to the form factors obscures or not such a dependence. We find that, using present data, it is possible in many cases to put a sensible lower bound to 1/R, the most stringent one coming from $B \to K^* \gamma$.