Nambu-Goldstone Modes in Gravitational Theories with Spontaneous Lorentz Breaking

TL;DR

This paper explores the fate of Nambu-Goldstone modes and the possibility of a Higgs mechanism in gravitational theories where Lorentz symmetry is spontaneously broken, relevant for quantum gravity and string theory.

Contribution

It reviews recent research on the behavior of Nambu-Goldstone modes and the potential for a Higgs mechanism in theories with spontaneous Lorentz symmetry breaking.

Findings

Nambu-Goldstone modes have specific characteristics in these theories.

A Higgs mechanism may or may not occur depending on the model.

Implications for quantum gravity and string theory are discussed.

Abstract

Spontaneous breaking of Lorentz symmetry has been suggested as a possible mechanism that might occur in the context of a fundamental Planck-scale theory, such as string theory or a quantum theory of gravity. However, if Lorentz symmetry is spontaneously broken, two sets of questions immediately arise: what is the fate of the Nambu-Goldstone modes, and can a Higgs mechanism occur? A brief summary of some recent work looking at these questions is presented here.