Polycritical Gravities

TL;DR

This paper introduces higher-derivative gravity theories that can propagate multiple gravitons with different masses on (A)dS backgrounds, featuring multiple critical points where graviton energies are non-negative, including some with positive energy.

Contribution

It develops a class of higher-derivative gravities with multiple gravitons and identifies critical points with non-negative and positive energies, expanding the landscape of consistent gravity theories.

Findings

Multiple graviton propagation on (A)dS backgrounds.

Existence of multiple critical points with degenerate masses.

Critical points with positive graviton energy for six derivatives and higher.

Abstract

We present higher-derivative gravities that propagate an arbitrary number of gravitons of different mass on (A)dS backgrounds. These theories have multiple critical points, at which the masses degenerate and the graviton energies are non-negative. For six derivatives and higher there are critical points with positive energy.