A remarkably simple covariant graviton propagator in Anti-de Sitter spacetime

Abstract

We present remarkably simple covariant expressions for the graviton and ghost propagators in Anti-de Sitter (AdS) spacetime valid in any spacetime dimension. In gravity there is a $2$-parameter family of covariant gauge-fixing conditions and the simplification occurs for a special choice of these parameters. In this gauge the graviton propagator satisfies $\nabla^μμ\nabla^νμ\, G_{μν,α'β'}(μ)=0$, where $μ$ is the geodesic distance between two points, and this condition implies an improved infrared behavior. This gauge choice is not possible in flat spacetime.