Hybrid Inflation in Supergravity

Abstract

We propose a simple realization of hybrid inflation in supergravity, which does not require any unnaturally small parameters. Inflation in this scenario is relatively short, and inflationary density perturbations fall down on large scales, which corresponds to a blue spectrum with n > 1. Superheavy strings which are formed after inflation in this scenario produce density perturbations of comparable magnitude. In this mixed perturbation (MP) model one may have microwave anisotropy produced by strings and galaxy formation due to inflationary perturbations.

Figures (2)

• Figure 1: The shape of density perturbations as a function of the number of e-folds for $\kappa = 0.1$. The horizon scale corresponds to $N \sim 60$. COBE normalization in this figure is shown as ${\delta\rho\over\rho} = 1$. Density perturbations sharply fall down on the scale corresponding to the beginning and the end of inflation.
• Figure 2: Deviation of the effective spectral index from $n =1$ at different scales for $\kappa = 0.1$. For $\kappa > 0.15$ the duration of inflation becomes smaller than $60$ e-folds, and the spectral index rapidly grows near the horizon.