Higgs Phenomenon for 4-D Gravity in Anti de Sitter Space

TL;DR

This paper demonstrates that in Anti de Sitter space, Einstein gravity coupled with a conformal field theory can experience a Higgs mechanism, giving the graviton a mass through boundary conditions and spectrum discreteness.

Contribution

It reveals a novel Higgs phenomenon for gravity in AdS space, highlighting boundary conditions and spectrum discreteness as key factors.

Findings

Graviton acquires mass via boundary conditions in AdS.

Discreteness of energy spectrum is crucial for the Higgs mechanism.

Boundary conditions imply a defect CFT at the AdS boundary.

Abstract

We show that standard Einstein gravity coupled to a free conformal field theory (CFT) in Anti de Sitter space can undergo a Higgs phenomenon whereby the graviton acquires a nonzero mass (and three extra polarizations). We show that the essential ingredients of this mechanism are the discreteness of the energy spectrum in AdS space, and unusual boundary conditions on the elementary fields of the CFT. These boundary conditions can be interpreted as implying the existence of a 3-d defect CFT living at the boundary of the AdS space. Our free-field computation sheds light on the essential, model-independent features of AdS that give rise to massive gravity.