Emergent Gravity from Vanishing Energy-Momentum Tensor

TL;DR

This paper shows how a vanishing energy-momentum tensor constraint can lead to emergent gravity as a nonperturbative phenomenon, with a composite graviton resembling Einstein gravity in a scalar field model.

Contribution

It provides a concrete example of emergent gravity from a scalar theory with vanishing energy-momentum tensor, demonstrating a composite massless spin-2 graviton.

Findings

Existence of a composite massless spin-2 graviton

Coupling of the graviton to matter as in Einstein gravity

Emergence of gravity as a nonperturbative artifact

Abstract

A constraint of vanishing energy-momentum tensor is motivated by a variety of perspectives on quantum gravity. We demonstrate in a concrete example how this constraint leads to a metric-independent theory in which quantum gravity emerges as a nonperturbative artifact of regularization-scale physics. We analyze a scalar theory similar to the Dirac-Born-Infeld (DBI) theory with vanishing gauge fields, with the DBI Lagrangian modulated by a scalar potential. In the limit of a large number of scalars, we explicitly demonstrate the existence of a composite massless spin-2 graviton in the spectrum that couples to matter as in Einstein gravity. We comment on the cosmological constant problem and the generalization to theories with fermions and gauge fields.