Non-singular inflation with vacuum decay

Abstract

On the basis of a semi-classical analysis of vacuum energy in an expanding spacetime, we describe a non-singular cosmological model in which the vacuum density decays with time, with a concomitant production of matter. During an infinitely long period we have an empty, inflationary universe, with H ≈ 1. This primordial era ends in a fast phase transition, during which H and Λ decrease to nearly zero in a few Planck times, with the release of a huge amount of radiation. The late-time scenario is similar to the standard model, with the radiation phase followed by a long dust era, which tends asymptotically to a de Sitter universe, with vacuum dominating again. An analysis of the redshift-distance relation for supernovae Ia leads to cosmological parameters in agreement with other current estimations.