Starobinsky-like inflation and running vacuum in the context of Supergravity

TL;DR

This paper presents a supergravity-based model of early Universe inflation driven by vacuum decay, which naturally transitions into standard cosmology and aligns with renormalization group ideas for evolving cosmological parameters.

Contribution

It introduces a supergravity framework where Starobinsky-like inflation arises from quantum corrections, incorporating vacuum decay and RG running of the cosmological constant.

Findings

The model achieves a graceful exit from inflation to radiation era.

Effective action structure aligns with RG running of vacuum energy.

Extension of the model covers subsequent cosmological epochs.

Abstract

We describe the primeval inflationary phase of the early Universe within a quantum field theoretical (QFT) framework that can be viewed as the effective action of vacuum decay in the early times. Interestingly enough, the model accounts for the "graceful exit" of the inflationary phase into the standard radiation regime. The underlying QFT framework considered here is Supergravity (SUGRA), more specifically an existing formulation in which the Starobinsky-type inflation (de-Sitter background) emerges from the quantum corrections to the effective action after integrating out the gravitino fields in their (dynamically induced) massive phase. We also demonstrate that the structure of the effective action in this model is consistent with the generic idea of renormalization group (RG) running of the cosmological parameters, specifically it follows from the corresponding RG equation for the vacuum energy density as a function of the Hubble rate, $\rho_{\Lambda}(H)$. Overall our combined approach amounts to a concrete-model realization of inflation triggered by vacuum decay in a fundamental physics context which, as it turns out, can also be extended for the remaining epochs of the cosmological evolution until the current dark energy era.