Cosmological perturbations in renormalization group derived cosmologies

A linear cosmological perturbation theory of an almost homogeneous and isotropic perfect fluid Universe with dynamically evolving Newton constant G and cosmological constant A is presented. A gauge invariant formalism is developed by means of the covariant approach, and the acoustic propagation equations governing the evolution of the comoving fractional spatial gradients of the matter density, G, and A are thus obtained. Explicit solutions are discussed in cosmologies where both G and A vary according to renormalization group equations in the vicinity of a fixed point.