Towards consistent extension of quasidilaton massive gravity

TL;DR

This paper introduces a new unitary Lorentz-invariant massive gravity theory extending quasidilaton models, which propagates all degrees of freedom on a homogeneous, isotropic de Sitter background, potentially advancing cosmological applications.

Contribution

It presents the first consistent, unitary extension of quasidilaton massive gravity with a novel coupling, maintaining symmetry and enabling propagation on a de Sitter background.

Findings

First example of a unitary Lorentz-invariant massive gravity theory

All degrees of freedom propagate on a homogeneous, isotropic de Sitter background

Introduces a new coupling between the graviton and quasidilaton scalar

Abstract

We present the first example of a unitary theory of Lorentz-invariant massive gravity, with all degrees of freedom propagating on a strictly homogeneous and isotropic, self-accelerating de Sitter background. The theory is a simple extension of the quasidilaton theory, respecting the symmetry of the original theory but allowing for a new type of coupling between the massive graviton and the quasidilaton scalar.