Background-independent composite gravity

We explore a background-independent model of composite gravity. In a mean-field approximation, the vacuum expectation value of the composite metric satisfies Einstein's equations (with corrections) as a consistency condition. A gravitational interaction then emerges in vacuum correlation functions. The action remains diffeomorphism invariant even as perturbation theory is organized about the dynamically selected vacuum spacetime. We discuss the role of nonphysical clock and rod fields in the analysis, the identification of physical observables, and the generalization to other theories including the standard model. (paper)