Cosmological perturbation analysis in a scale invariant model of gravity

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 such as the gravitational constant and the cosmological constant etc are generated by a solution of the classical equations of motion. Hence, this solution provides a mechanism to break 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. This demonstrates the robustness of this symmetry breaking mechanism.