All Fierz-Paulian massive gravity theories have ghosts or superluminal modes

TL;DR

This paper demonstrates that all non-linear Fierz-Pauli massive gravity theories either contain ghosts or exhibit superluminal modes, ruling out their viability.

Contribution

It proves that no ghost-free, non-linear completion of Fierz-Pauli massive gravity can avoid superluminal modes, establishing a no-go result.

Findings

All ghost-free theories have superluminal modes

Non-linear Fierz-Pauli massive gravity theories are ruled out

Ghosts or superluminal modes are unavoidable

Abstract

We show that all non-linear completions of the Fierz-Pauli massive gravity are ruled out, because all theories which might be ghost-free have superluminal modes.