A unitary renormalizable model of composite gravitons

TL;DR

This paper proposes a novel, unitary, and renormalizable local field theory model of gravity based on a confining SU(4) Yang-Mills framework with composite spin-2 excitations that could serve as gravitons.

Contribution

It introduces the first explicit, perturbatively-renormalizable local field theory model of gravity with composite gravitons derived from a confining gauge theory.

Findings

Presence of light or condensed spin-2 excitations with graviton-like properties.

Existence of a massless spin-2 Goldstone boson under certain conditions.

Coupling mechanisms for these fields to matter are discussed.

Abstract

A four-dimensional ${\rm SU}(4)$ confining Yang-Mills field, coupled to a fundamental fermion field and a bi-fundamental scalar field, has excitations with spin-2, but no other quantum numbers. These spin-2 excitations can be light or can condense, depending upon the scalar coupling. If condensation occurs, there is a massless spin-2 Goldstone boson with (possibly weakly) broken Lorentz invariance in the effective theory. The low-lying spectrum contains additional spin-0 and spin-1 particles. We discuss how to couple these new fields to other matter fields. To our knowledge, this is the only explicit proposal for a unitary and perturbatively-renormalizable local field theory of gravity.