On Bose-Einstein condensation on closed Robertson-Walker spacetimes

TL;DR

This paper investigates Bose-Einstein condensation in closed Robertson-Walker spacetimes, analyzing the effects of finite spatial volume and identifying a critical radius where the condensate forms or disappears.

Contribution

It introduces an analysis of Bose-Einstein condensation on closed Robertson-Walker spacetimes using an adiabatic KMS state, highlighting the role of the critical radius.

Findings

Finite spatial volume effects are negligible in the early universe.

A critical radius for Bose-Einstein condensation is identified.

Condensate disappears above the critical radius.

Abstract

In this letter we summarize our analysis of Bose-Einstein condensation on closed Robertson-Walker spacetimes. In a previous work we defined an adiabatic KMS state on the Weyl-algebra of the free massive Klein-Gordon field. This state describes a free Bose gas on Robertson-Walker spacetimes. We use this state to analyze the possibility of Bose-Einstein condensation on closed Robertson-Walker spacetimes. We take into account the effects due to the finiteness of the spatial volume and show that they are not relevant in the early universe. Furthermore we show that a critical radius can be defined. The condensate disappears above the critical radius.