Unified cosmology with Non-minimally coupled scalar-tensor theory of gravity

TL;DR

This paper explores a non-minimally coupled scalar-tensor gravity theory that unifies early inflation and late-time cosmic acceleration through a conserved current linked to the trace of the energy-momentum tensor.

Contribution

It introduces a novel conserved current in scalar-tensor gravity that facilitates a unified cosmological model connecting early and late universe acceleration phases.

Findings

Existence of a conserved current in specific conditions

Symmetry during early vacuum and radiation eras

Unification of inflation and dark energy phenomena

Abstract

Unlike Noether symmetry, a metric independent general conserved current exits for non-minimally coupled scalar-tensor theory of gravity, if the trace of the energy momentum tensor vanishes. Thus, in the context of cosmology, a symmetry exists both in the early vacuum and radiation dominated era. For slow roll, symmetry is sacrificed, but at the end of early inflation, such a symmetry leads to a Friedmann-like radiation era. Late time cosmic acceleration in the matter dominated era is realized in the absence of symmetry, in view of the same decayed and red-shifted scalar field. Thus, unification of early inflation with late time cosmic acceleration with a single scalar field, may be realized.