Textures and Semi-Local Strings in SUSY Hybrid Inflation

TL;DR

This paper investigates supersymmetric hybrid inflation models with SU(2) symmetry, predicting textures and semi-local strings that could explain the CMB cold spot, while addressing gravitino overproduction and matching observed power spectra.

Contribution

It introduces a novel SUSY hybrid inflation model with SU(2) symmetry, predicting textures and semi-local strings, and analyzes their cosmological implications.

Findings

Models predict global textures and semi-local strings.

Reheating via light SU(2)-modes avoids gravitino overproduction.

Inflation scale aligns with cold spot explanation.

Abstract

Global topological defects may account for the large cold spot observed in the Cosmic Microwave Background. We explore possibilities of constructing models of supersymmetric F-term hybrid inflation, where the waterfall fields are globally SU(2)-symmetric. In contrast to the case where SU(2) is gauged, there arise Goldstone bosons and additional moduli, which are lifted only by masses of soft-supersymmetry breaking scale. The model predicts the existence of global textures, which can become semi-local strings if the waterfall fields are gauged under U(1)_X. Gravitino overproduction can be avoided if reheating proceeds via the light SU(2)-modes or right-handed sneutrinos. For values of the inflaton- waterfall coupling >=10^-4, the symmetry breaking scale imposed by normalisation of the power spectrum generated from inflation coincides with the energy scale required to explain the most prominent of the cold spots. In this case, the spectrum of density fluctuations is close to scale-invariant which can be reconciled with measurements of the power spectrum by the inclusion of the sub-dominant component due to the topological defects.