Inflection point inflation within supersymmetry

TL;DR

This paper proposes a model for inflection point inflation within supersymmetry that reduces fine-tuning by introducing a temporary vacuum energy from a phase transition, linked to an extended gauge group.

Contribution

It introduces a novel inflation model that minimizes fine-tuning by utilizing a false vacuum from an extended gauge symmetry, specifically U(1)_{B-L}, during inflation.

Findings

Fine-tuning is significantly reduced with the added vacuum energy.

The model requires a small U(1)_{B-L} gauge coupling g_{B-L} ≤ 10^{-4}.

The proposed mechanism aligns with supersymmetric flat directions during inflation.

Abstract

We propose to address the fine tuning problem of inflection point inflation by the addition of extra vacuum energy that is present during inflation but disappears afterwards. We show that in such a case, the required amount of fine tuning is greatly reduced. We suggest that the extra vacuum energy can be associated with an earlier phase transition and provide a simple model, based on extending the SM gauge group to SU(3)_C \times SU(2)_L\times U(1)_Y\times U(1)_{B-L}, where the Higgs field of U(1)_{B-L} is in a false vacuum during inflation. In this case, there is virtually no fine tuning of the soft SUSY breaking parameters of the flat direction which serves as the inflaton. However, the absence of radiative corrections which would spoil the flatness of the inflaton potential requires that the U(1)_{B-L} gauge coupling should be small with g_{B-L}\leq 10^{-4}.