Elementary particle interaction from a Kaluza-Klein scheme

It is well-expected that unifying gravity with other interactions requires a decisive change of perspective on some of our ideas. We can mention String Theory as the most suggestive approach in this direction. Here we are going to focus our attention on the Kaluza-Klein (KK) approach 1,2 (see 3 for a recent review), since it realizes the issue of the unification, without avoiding one of the most impressive results of Theoretical Physics: the geometrization of the gravitational field. Furthermore, such models provide a description of gauge bosons as components of the metric tensor, in a space-time with more than 4 dimensions. The presence of such extra-coordinates does not conflict with a 4phenomenology, as soon as they are compactified to very small distances. This scenario is not so unusual, because we know that in the very Early Universe the compactification of some dimensions is expected. Being undetectable in a direct