Modified hybrid inflation in no-scale SUGRA with suppressed $R$-symmetry breaking

TL;DR

This paper proposes a modified hybrid inflation model within no-scale supergravity, incorporating suppressed R-symmetry breaking terms, resulting in inflationary predictions compatible with observations and similar to Starobinsky inflation.

Contribution

It introduces a specific R-symmetry breaking term in no-scale SUGRA hybrid inflation, achieving successful inflation with observable tensor-to-scalar ratio and spectral index.

Findings

Tensor-to-scalar ratio r ~ 10^{-2}

Spectral index n_s ≈ 0.965

Potential similar to Starobinsky model

Abstract

A well-motivated cosmological hybrid inflation scenario based on no-scale SUGRA is considered. It is demonstrated that an extra suppressed $R$-symmetry breaking term $S^n$ with $n\geq 4$ needs to be included in order to realize successful inflation. The resulting potential is found to be similar (but not identical) to the one in the Starobinsky inflation model. A relatively larger tensor-to-scalar ratio $r\sim 10^{-2}$ and a spectral index $n_s\approx 0.965$ are obtained, which are approximately independent of $n$.