Cosmological Perturbation Analysis in a Scale Invariant Model of Gravity

TL;DR

This paper investigates a scale-invariant gravity model with a scalar field, demonstrating the stability of its solutions against small perturbations in a flat FRW universe, highlighting its potential for cosmological applications.

Contribution

It introduces a scale-invariant gravity model with a scalar field and analyzes the stability of its solutions under linear perturbations.

Findings

The model's solutions are stable against small perturbations.

Dimensionful parameters emerge dynamically from the model.

The analysis supports the viability of scale-invariant gravity in cosmology.

Abstract

We consider a model for gravity that is invariant under global scale transformations. It includes one extra real scalar field coupled non-minimally to the gravity fields. In this model all the dimensionful parameters like the gravitational constant and the cosmological constant etc. are generated by a solution of the classical equations of motion which breaks scale invariance. In this paper we demonstrate the stability of such a solution against small perturbations in a flat FRW background by making a perturbative expansion around this solution and solving the resulting equations linear in the perturbations.