Unification of Inflation and Dark Energy from Spontaneous Breaking of Scale Invariance

Abstract: We propose a new class of gravity-matter models defined in terms of two independent non-Riemannian volume forms (alternative generally covariant integration measure densities) on the spacetime manifold. For the matter we choose appropriate scalar field potentials of exponential form so that the full gravity-matter system is invariant under global Weyl-scale symmetry. Solution of the pertinent equations of motion produce two dimensionful integration constants which spontaneously break global Weyl-scale invariance. In the resulting effective Einstein-frame gravity-matter system we obtain an effective potential for the scalar matter field which has an interesting cosmological application, namely, it allows for a unified description of both an early universe inflation and present day dark energy.