Cosmology is not a Renormalization Group Flow

TL;DR

This paper critically examines two models proposing cosmology as a renormalization group flow, demonstrating their failure in a scalar field model and emphasizing particle production as the main driver of cosmological evolution.

Contribution

It provides a critical analysis showing that cosmology cannot be accurately described as a renormalization group flow in certain scalar field models.

Findings

Both RG-based models fail in the scalar field context.

Cosmological evolution is driven by particle production, not RG screening.

Inflationary particle production fills the universe with long wavelength scalars.

Abstract

A critical examination is made of two simple implementations of the idea that cosmology can be viewed as a renormalization group flow. Both implementations are shown to fail when applied to a massless, minimally coupled scalar with a quartic self-interaction on a locally de Sitter background. Cosmological evolution in this model is not driven by any RG screening of couplings but rather by inflationary particle production gradually filling an initially empty universe with a sea of long wavelength scalars.