De Sitter Waves and the Zero Curvature Limit

TL;DR

The paper demonstrates that a specific set of global modes for the massive de Sitter scalar field facilitates the flat space limit, confirming the Euclidean vacuum's suitability for recovering standard QFT.

Contribution

It introduces a method using de Sitter waves to manage group representations and Fourier transforms in the flat limit, challenging previous negative energy concerns.

Findings

De Sitter waves enable a proper flat limit transition.

Euclidean vacuum is confirmed as the preferred vacuum state.

The approach manages group representations effectively in the limit.

Abstract

We show that a particular set of global modes for the massive de Sitter scalar field (the de Sitter waves) allows to manage the group representations and the Fourier transform in the flat (Minkowskian) limit. This is in opposition to the usual acceptance based on a previous result, suggesting the appearance of negative energy in the limit process. This method also confirms that the Euclidean vacuum, in de Sitter spacetime, has to be preferred as far as one wishes to recover ordinary QFT in the flat limit.