Inflation in no-scale supergravity

TL;DR

This paper explores modifications of superpotentials in no-scale supergravity models, generalizing the Starobinsky inflation model, and finds that these models predict a small tensor-to-scalar ratio consistent with recent cosmological observations.

Contribution

It introduces new superpotential modifications within no-scale supergravity that produce viable inflationary models with low tensor-to-scalar ratios.

Findings

Models predict a small tensor-to-scalar ratio, below current observational bounds.

Modified superpotentials can still produce successful single-field slow-roll inflation.

Results are consistent with recent PLANCK and BICEP2 data.

Abstract

$R+R^2$ Supergravity is known to be equivalent to standard Supergravity coupled to two chiral supermultiples with a no-scale K\"ahler potential. Within this framework, that can accomodate vanishing vacuum energy and spontaneous supersymmetry breaking, we consider modifications of the associated superpotential and study the resulting models, which, viewed as generalizations of the Starobinsky model, for a range of the superpotential parameters, describe viable single-field slow-roll inflation. In all models studied in this work the tensor to scalar ratio is found to be small, well below the upper bound established by the very recent PLANCK and BICEP2 data.