Evolution of cosmological perturbations in an RG-driven inflationary scenario

TL;DR

This paper develops a gauge-invariant perturbation theory for an almost homogeneous universe with evolving G and Λ, analyzing their behavior during accelerated expansion and near fixed points in RG flow.

Contribution

It introduces a novel gauge-invariant framework for cosmological perturbations with dynamical G and Λ, applying RG equations near fixed points in both early and late universe regimes.

Findings

Explicit solutions for perturbations during accelerated expansion with varying G and Λ.

Analysis of perturbation evolution near ultraviolet and Gaussian fixed points.

Insights into the impact of RG flow on cosmological structure formation.

Abstract

A gauge-invariant, linear cosmological perturbation theory of an almost homogeneous and isotropic universe with dynamically evolving Newton constant G and cosmological constant $\Lambda$ is presented. The equations governing the evolution of the comoving fractional spatial gradients of the matter density, G and $\Lambda$ are thus obtained. Explicit solutions are discussed in cosmologies, featuring an accelerated expansion, where both G and $\Lambda$ vary according to renormalization group equations in the vicinity of an ultraviolet fixed point. Finally, a similar analysis is carried out in the late universe regime described by the part of the renormalization group trajectory close to the gaussian fixed point.