Inverted Hybrid Inflation as a solution to gravitino problems in Gravity Mediation

TL;DR

This paper proposes inverted hybrid inflation as a viable solution to gravitino overproduction in gravity mediation, also explaining baryon asymmetry and aligning with observational data.

Contribution

It introduces inverted hybrid inflation as a novel model that addresses gravitino problems and is compatible with cosmological observations.

Findings

Solves gravitino overproduction problem

Explains baryon asymmetry via non-thermal leptogenesis

Consistent with WMAP data on spectral index and tensor ratio

Abstract

It was recently found that the decay of inflaton and the SUSY breaking field produces many gravitinos in the gravity mediation scenario. These discoveries led to an exclusion of many inflation models such as chaotic, (smooth) hybrid, topological and new inflation models. Under these circumstances we searched for a successful inflation model and found that the ``inverted'' hybrid inflation models can solve the gravitino overproduction problem by their distinctive shape of the potential. Furthermore, we found that this inflation model simultaneously can explain the observed baryon asymmetry through the non-thermal leptogenesis and is consistent with the WMAP results, that is, $n_s=0.951^{+0.015}_{-0.019}$ and the negligible tensor to scalar ratio.