Mixed metric perturbations in Kaluza-Klein cosmologies

Abstract

We consider metric perturbations of Kaluza-Klein cosmological models filled with phenomenological matter. We find the exact solution for the development in time of the mixed perturbations, which have one index in the ordinary and one in the internal space. The initial values are assumed to be taken as quantum fluctuation. The contraction of the internal scales produces effectively massive wave modes in the ordinary space. The comparison of this particle creation with dark-matter estimations informs us about the fundamental parameters of the model.