Covariant constraints for generic massive gravity and analysis of its characteristics

TL;DR

This paper provides a covariant constraint analysis of massive gravity, confirming it propagates five degrees of freedom, and discusses its characteristics including superluminality and acausalities.

Contribution

It offers a comprehensive covariant constraint framework for massive gravity and introduces a streamlined Hamiltonian approach to verify degrees of freedom.

Findings

Propagates five degrees of freedom across parameter space

Identifies superluminality and acausalities in the model

Enables computation of caustics using covariant constraints

Abstract

We perform a covariant constraint analysis of massive gravity valid for its entire parameter space, demonstrating that the model generically propagates five degrees of freedom; this is also verified by a new and streamlined Hamiltonian description. The constraint's covariant expression permits computation of the model's caustics. Although new features such as the dynamical Riemann tensor appear in the characteristic matrix, the model still exhibits the pathologies uncovered in earlier work: superluminality and likely acausalities.