Two-stage inflation as a solution to the initial condition problem of hybrid inflation

Abstract

We address the issue of fine-tuning of the initial field configuration that can lead to hybrid inflation in the context of global supersymmetry. This problem is generated by the difference between the energy scale at which the Universe emerges from the Planck era and the inflationary scale implied by the COBE observations: ${V}^{1/4}\ensuremath{\sim}{10}^{\ensuremath{-}3}{m}_{\mathrm{Pl}}.$ We propose a scenario with two stages of inflation. The first stage, with a typical scale not far from ${m}_{\mathrm{Pl}},$ occurs ``naturally'' and provides the necessary homogeneity for the second stage. The latter generates the density perturbations that result in the cosmic microwave background anisotropy observed by COBE.