Massive gravitons in arbitrary spacetimes

TL;DR

This paper develops two practical theories of massive gravitons in arbitrary spacetimes, showing they propagate five degrees of freedom, are stable if sufficiently massive, and could be relevant for dark matter.

Contribution

It introduces two consistent, practical formulations of massive gravitons applicable to arbitrary spacetimes, extending previous models and analyzing their properties.

Findings

Massive gravitons propagate five degrees of freedom in arbitrary spacetimes.

Gravitons are stable if sufficiently massive, potentially contributing to dark matter.

Theories reproduce known results in Einstein spaces and are applicable to cosmological backgrounds.

Abstract

We present two different versions of the consistent theory of massive gravitons in arbitrary spacetimes which are simple enough for practical applications. The theory is described by a non-symmetric rank-2 tensor whose equations of motion imply six algebraic and five differential constraints reducing the number of independent components to five. The theory reproduces the standard description of massive gravitons in Einstein spaces. In generic spacetimes it does not show the massless limit and always propagates five degrees of freedom, even for the vanishing mass parameter. We illustrate these features by an explicit calculation for a homogeneous and isotropic cosmological background. We find that the gravitons are stable if they are sufficiently massive, hence they may be a part of Dark Matter at present. We discuss also other possible applications.