Quintessential inflation from a variable cosmological constant in a 5D vacuum

TL;DR

This paper presents a 4D cosmological model derived from a 5D vacuum, where a variable cosmological constant and inflaton field drive the universe's expansion, with implications for the inflaton-gravity coupling over cosmic epochs.

Contribution

It introduces a novel 4D cosmological framework from a 5D vacuum with a nonminimally coupled inflaton, emphasizing a variable inflaton-gravity interaction.

Findings

The cosmological constant remains negative during expansion.

The inflaton field is nonminimally coupled to gravity.

The inflaton-gravity coupling varies across different cosmic epochs.

Abstract

We explore an effective 4D cosmological model for the universe where the variable cosmological constant governs its evolution and the pressure remains negative along all the expansion. This model is introduced from a 5D vacuum state where the (space-like) extra coordinate is considered as noncompact. The expansion is produced by the inflaton field, which is considered as nonminimally coupled to gravity. We conclude from experiental data that the coupling of the inflaton with gravity should be weak, but variable in different epochs of the evolution of the universe.