Entropy Production during Asymptotically Safe Inflation

TL;DR

This paper explores how asymptotically safe quantum gravity can naturally induce inflation in the early universe without an inflaton, driven by quantum effects and leading to entropy generation.

Contribution

It demonstrates that asymptotic safety in quantum gravity can produce inflationary expansion and entropy generation without additional scalar fields.

Findings

Inflation arises from quantum gravity effects without an inflaton.

The model naturally ends inflation as vacuum energy decreases.

Entropy of the universe can be generated by quantum gravity mechanisms.

Abstract

The Asymptotic Safety scenario predicts that the deep ultraviolet of Quantum Einstein Gravity is governed by a nontrivial renormalization group fixed point. Analyzing its implications for cosmology using renormalization group improved Einstein equations we find that it can give rise to a phase of inflationary expansion in the early Universe. Inflation is a pure quantum effect here and requires no inflaton field. It is driven by the cosmological constant and ends automatically when the renormalization group evolution has reduced the vacuum energy to the level of the matter energy density. The quantum gravity effects also provide a natural mechanism for the generation of entropy. It could easily account for the entire entropy of the present Universe in the massless sector.