Natural Chaotic Inflation in Supergravity

TL;DR

The paper tackles realizing chaotic inflation in supergravity, where the usual exponential factor makes large-field inflation problematic. It introduces a Nambu-Goldstone-like shift symmetry for the inflaton in the Kähler potential and a small symmetry-breaking term in the superpotential, enabling chaotic inflation with stabilized auxiliary fields. The COBE normalization fixes the inflaton mass scale around ten to thirteen GeV, and reheating proceeds via a small Higgs coupling consistent with gravitino bounds; higher-order Kahler corrections are controlled and the construction is natural in the 't Hooft sense. This work provides a symmetry-based route to large-field inflation in supergravity and suggests that tensor modes could be detectable by Planck/MAP, marking a new direction for inflation-model building.

Abstract

We propose a chaotic inflation model in supergravity. In the model the Kähler potential has a Nambu-Goldstone-like shift symmetry of the inflaton chiral multiplet which ensures the flatness of the inflaton potential beyond the Planck scale. We show that the chaotic inflation naturally takes place by introducing a small breaking term of the shift symmetry in the superpotential. This may open a new branch of model building for inflationary universe in the framework of supergravity.