Energy Density of Non-Minimally Coupled Scalar Field Cosmologies

TL;DR

This paper derives an expression for the energy density of non-minimally coupled scalar fields in cosmological backgrounds, revealing how coupling affects effective mass, symmetry breaking, and stability.

Contribution

It provides a new formulation of scalar energy density in non-minimally coupled cosmologies, highlighting the impact of coupling on mass, symmetry, and stability.

Findings

Effective scalar mass depends explicitly on coupling and scale factor.

Self-coupling can vanish for specific coupling values.

Gravitational effects can induce symmetry breaking and destabilization.

Abstract

Scalar fields coupled to gravity via $\xi R {\Phi}^2$ in arbitrary Friedmann-Robertson-Walker backgrounds can be represented by an effective flat space field theory. We derive an expression for the scalar energy density where the effective scalar mass becomes an explicit function of $\xi$ and the scale factor. The scalar quartic self-coupling gets shifted and can vanish for a particular choice of $\xi$. Gravitationally induced symmetry breaking and de-stabilization are possible in this theory.