Modelli Inflazionari e le loro caratteristiche di universalità

Recently some new approaches to study the dynamics of the accelerated expansion of the early universe (inflation) has been proposed. These new approaches, that exploit a Hamilton-Jacobi formalism to the inflationary evolution of the universe, allow to put in evidence a universal behaviour in such a dynamics with corresponding universal features in the observational redictions (about the primordial density perturbations and the predicted primordial gravitational waves). This allows to pin down wide classes of inflationary models sharing similar characteristics. The thesis will consist first of all in a review of this kind of approach and its phenomenological consequences for different kind of inflation (slow-roll, k-inflation, anisotropic inflation).