Non-perturbative Unitarity of Gravitational Higgs Mechanism

TL;DR

This paper investigates the unitarity of massive gravity via gravitational Higgs mechanism, providing a non-perturbative framework and analyzing the full nonlinear Hamiltonian to ensure the absence of negative norm states.

Contribution

It introduces a non-perturbative definition of massive gravity through gravitational Higgs mechanism and examines unitarity beyond perturbation theory.

Findings

No negative norm states in the full nonlinear theory

Perturbative unitarity is not evident, but non-perturbative analysis suggests unitarity is preserved

Provides a non-perturbative framework for massive gravity

Abstract

In this paper we discuss massive gravity in Minkowski space via gravitational Higgs mechanism, which provides a non-perturbative definition thereof. Using this non-perturbative definition, we address the issue of unitarity by studying the full nonlinear Hamiltonian for the relevant metric degrees of freedom. While perturbatively unitarity is not evident, we argue that no negative norm state is present in the full nonlinear theory.