$R$-Symmetry Breaking in Supersymmetric Hybrid Inflation

TL;DR

This paper explores how explicit breaking of U(1) R-symmetry via Planck-suppressed operators influences supersymmetric hybrid inflation, analyzing the resulting inflationary potential and its compatibility with observational data.

Contribution

It introduces a minimal Kähler potential model with R-symmetry breaking term $ ext{α} S^4$, examining its effects on inflationary predictions and constraints.

Findings

Successful inflation with spectral index $n_s \,\approx 0.97$

Tensor-to-scalar ratio $r \,\lesssim 10^{-4}$

R-symmetry breaking parameter $|\alpha| \lesssim 10^{-7}$

Abstract

We consider a supersymmetric hybrid inflation scenario in which the U(1) $R$-symmetry is explicitly broken by Planck scale suppressed operators in the superpotential. We provide an example with minimal K\"ahler potential, with the $R$-symmetry breaking term relevant during inflation being $\alpha S^4$, where $S$ denotes the well-known gauge singlet inflaton superfield. The inflationary potential takes into account the radiative and supergravity corrections, as well as the soft supersymmetry breaking terms. For successful inflation, with the scalar spectral index in the currently preferred range, $n_s \approx 0.97 \pm 0.010$, $| \alpha |$ $\lesssim 10^{-7}$. The tensor to scalar ratio $r \lesssim 10^{-4}$, while $| \text{d} n_s / \text{d} \ln k | \sim \mathcal{O}(10^{-3})-\mathcal{O}(10^{-4})$