Flat Potential for Inflaton with a Discrete <i>R</i>-Invariance in Supergravity

Abstract

We show that a very flat potential of inflaton required for a sufficient inflation is naturally obtained in N = 1 supergravity by imposing a discrete R-invariance Zn (n ≥3). Several cosmological constraints on parameters in the inflaton superpotential are derived. The reheating temperature turns out to be (1 - 108) GeV for the cases n = 3 - 10. Baryogenesis in this model is also discussed briefly.