Graviton Propagator in a General Invariant Gauge on de Sitter

TL;DR

This paper constructs the graviton propagator on de Sitter space in a family of invariant gauges, revealing universal de Sitter breaking behavior and correcting previous assumptions based on analytic continuation methods.

Contribution

It provides the first explicit form of the graviton propagator in a general invariant gauge on de Sitter, highlighting the universal de Sitter breaking feature.

Findings

No de Sitter invariant solution for the structure functions.

De Sitter breaking is universal for the graviton propagator.

Certain gauge choices can eliminate the spin zero de Sitter breaking contribution.

Abstract

We construct the graviton propagator on de Sitter background in the one parameter family of exact, de Sitter invariant gauges. Our result takes the form of a universal spin two part and a gauge dependent spin zero part. Scalar equations are derived for the structure functions of each part. There is no de Sitter invariant solution for either structure function, although the de Sitter breaking contribution to the spin zero part may drop out for certain choices of the gauge parameter. Our results imply that de Sitter breaking is universal for the graviton propagator, and hence that there is an error in the contrary results derived by analytic continuation of average gauge fixing techniques.