Regularized vacuum stress tensor of a scalar field as the inflaton or dark energy

TL;DR

This paper investigates the vacuum stress tensor of scalar fields in symmetric spacetime to evaluate their potential as inflaton or dark energy candidates, highlighting the role of coupling and mass.

Contribution

It demonstrates that conformally coupled scalar fields with large mass can drive inflation or dark energy, unlike minimally coupled fields.

Findings

Conformally coupled scalar with ~10 M_pl can be inflaton or dark energy.

Minimally coupled scalar fields cannot serve as inflaton or dark energy.

Quantum origin may unify inflaton and dark energy components.

Abstract

We study the regularized vacuum stress tensor of scalar fields in maximally symmetric spacetime and assess the feasibility of driving primordial inflation or current cosmic acceleration by analyzing the existence of solutions to the Friedmann equation. We find that a conformally coupled scalar field with mass of order $10$ $M_{\text{pl}}$ can be a candidate for both the inflaton and dark energy, suggesting that these two components may have the same quantum origin. In contrast, a minimally coupled scalar field cannot serve as either the inflaton or dark energy regardless of its mass.