A new quasidilaton theory of massive gravity

TL;DR

This paper introduces a novel quasidilaton massive gravity theory with a unique matter coupling framework, yielding a stable self-accelerating de Sitter solution with positive effective Newton's constant.

Contribution

It proposes a new quasidilaton theory based on matter coupling allowing kinetic energy interaction with both metrics, and demonstrates its stability and self-acceleration solutions.

Findings

Existence of a self-accelerating de Sitter solution

Stable linear perturbations with positive kinetic terms

Positive effective Newton's constant in the model

Abstract

We present a new quasidilaton theory of Poincare invariant massive gravity, based on the recently proposed framework of matter coupling that makes it possible for the kinetic energy of the quasidilaton scalar to couple to both physical and fiducial metrics simultaneously. We find a scaling-type exact solution that expresses a self-accelerating de Sitter universe, and then analyze linear perturbations around it. It is shown that in a range of parameters all physical degrees of freedom have non-vanishing quadratic kinetic terms and are stable in the subhorizon limit, while the effective Newton's constant for the background is kept positive.