Natural chaotic inflation in supergravity and leptogenesis

Abstract

We propose a chaotic inflation model in supergravity. In this model, the form of Kähler potential is determined by a symmetry, that is, the Nambu-Goldstone like shift symmetry, which guarantees the absence of the exponential factor in the potential for the inflation field. Though we need introduction of small parameters, the smallness of parameters is justified also by symmetries. That is, the zero limit of small parameters recovers symmetries, which is natural in ’t Hooft’s sense. The leptogenesis scenario via the inflation decay in this chaotic inflation model is also discussed. We find that the lepton asymmetry enough to explain the present baryon number density is produced for low reheating temperatures avoiding the overproduction of gravitinos.