Reducing the Spectral Index in Supernatural Inflation

TL;DR

This paper demonstrates how supernatural inflation models can naturally produce a spectral index of 0.96, aligning with observational data, without requiring fine-tuning, by incorporating non-renormalizable terms with A-terms.

Contribution

It introduces a mechanism within supernatural inflation to achieve the observed spectral index without fine-tuning, using non-renormalizable terms and A-terms.

Findings

Spectral index reduced to 0.96

No fine-tuning needed for the model

Consistent with observational data

Abstract

Supernatural inflation is an attractive model based just on a flat direction with soft SUSY breaking mass terms in the framework of supersymmetry. The beauty of the model is inferred from its name that the model needs no fine-tuning. However, the prediction of the spectral index is $n_s \gae 1$, in contrast to experimental data. In this paper, we show that the beauty of supernatural inflation with the spectral index reduced to $n_s=0.96$ without any fine-tuning, by considering the general feature that a flat direction is lifted by a non-renormalizable term with an A-term.