2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/189350Exclusive rare $B \to K^{(*)} \ell^+ \ell^-$, $B \to K^{(*)} ν\bar ν$ and $B \to K^* γ$ 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 $B \to K^* γ$.LaTeX, 4 pages, 4 figures. Talk given at "QCD 06", July 3-7 2006, Montpellier (France)High Energy Physics - Phenomenologytext