Infrared instability of the de Sitter space

TL;DR

This paper investigates the infrared instabilities of de Sitter space, revealing IR/UV mixing, non-renormalizability, and backreaction effects, which challenge the stability of the expanding universe and relate to Gibbons-Hawking radiation.

Contribution

It demonstrates that de Sitter space exhibits IR divergences and instabilities due to IR/UV mixing, impacting the understanding of quantum fields in expanding universes.

Findings

Massive particles cause IR divergences and backreaction.

Expanding universe shows weaker instability.

Gibbons-Hawking radiation is linked to these instabilities.

Abstract

We continue to investigate various instabilities of the fixed backgrounds related to the de Sitter space. It is shown that in many cases the in/in perturbation theory contains IR/UV mixing and thus is non-renormalizible. The application of this result to the global de Sitter space leads to the conclusion that even massive particles generate IR divergence and the huge back reaction. The expanding universe is also unstable but in a weaker sense. We further discuss, the strange features of the Gibbons-Hawking radiation and its relation to the above instabilities. .