Physical meaning and consequences of the loop IR divergences in global dS

TL;DR

This paper investigates how loop IR divergences in global de Sitter space break its isometry symmetry, derives a kinetic equation from the Dyson-Schwinger framework, and explores the physical implications, including particle production.

Contribution

It introduces a kinetic equation for global de Sitter space derived from the Dyson-Schwinger approach, revealing the physical effects of IR divergences and isometry breaking.

Findings

Loop IR divergences break de Sitter isometry in global space.

Kinetic equation describes IR effects and particle dynamics.

Explosive particle production occurs under certain initial conditions.

Abstract

Following arXiv:1012.2107 we show that in global de Sitter space its isometry is broken by the loop IR divergences for any invariant vacuum state of the massive scalars. We derive kinetic equation in global de Sitter space. It follows from the Dyson-Schwinger equation of the Schwinger-Keldysh diagrammatic technique in IR limit and allows to understand the physical meaning and consequences of the loop IR divergences. In many respects the isometry breaking in global dS is similar to the one in the contracting Poincare patch of de Sitter space. Hence, as a warm up exercise we study the kinetic equation and properties of its solutions in the expanding and contracting Poincare patches of de Sitter space. Quite unexpectedly we find that under some initial conditions there is an explosive production of massive particles in the expanding Poincare patch.