Flipped GUT Inflation

TL;DR

This paper explores hybrid inflation models based on flipped SU(5)$\times$U(1), identifying parameter regions compatible with observational data and discussing embeddings into SO(10) to address monopole issues.

Contribution

It introduces flipped SU(5)$\times$U(1) inflation models with specific inflaton candidates and analyzes their compatibility with cosmological observations, including potential embeddings into SO(10).

Findings

Models compatible with $A_s$, $n_s$, and $r$ constraints.

Inflation can occur with sneutrino or gauge singlet inflaton.

Embedding into SO(10) addresses monopole problems.

Abstract

We analyse the prospects for constructing hybrid models of inflation that provide a dynamical realisation of the apparent closeness between the supersymmetric GUT scale and the possible scale of cosmological inflation. In the first place, we consider models based on the flipped SU(5)$\times$U(1) gauge group, which has no magnetic monopoles. In one model, the inflaton is identified with a sneutrino field, and in the other model it is a gauge singlet. In both cases we find regions of the model parameter spaces that are compatible with the experimental magnitudes of the scalar perturbations, $A_s$, and the tilt in the scalar perturbation spectrum, $n_s$, as well as with an indicative upper limit on the tensor-to-scalar perturbation ratio, $r$. We also discuss embeddings of these models into SO(10), which is broken at a higher scale so that its monopoles are inflated away.