Exotic Massive 3D Gravity

TL;DR

Exotic Massive Gravity is a novel 3D gravity theory that extends New Massive Gravity with a parity-odd action, introducing a new class of third-way consistent models with unique properties.

Contribution

It introduces Exotic Massive Gravity, a new third-way consistent 3D gravity model with a parity-odd action, expanding the landscape of massive gravity theories.

Findings

Propagates a parity doublet of massive spin-2 modes.

Features a Chern-Simons-like, parity-odd action.

Part of an infinite sequence of third-way consistent theories.

Abstract

The linearized equations of `New Massive Gravity' propagate a parity doublet of massive spin-2 modes in 3D Minkowski spacetime, but a different non-linear extension is made possible by `third-way' consistency. There is a `Chern-Simons-like' action, as for other 3D massive gravity models, but the new theory is `exotic': its action is parity odd. This `Exotic Massive Gravity' is the next-to-simplest case in an infinite sequence of third-way consistent 3D gravity theories, the simplest being the `Minimal Massive Gravity' alternative to `Topologically Massive Gravity'.