Gauge Assisted Quadratic Gravity: A Framework for UV Complete Quantum Gravity

TL;DR

This paper proposes a gauge-assisted quadratic gravity framework where a Yang-Mills interaction helps induce Einstein-Hilbert gravity, maintaining weak coupling at all energies and providing a potential UV complete quantum gravity theory.

Contribution

It introduces a novel quadratic gravity model assisted by Yang-Mills theory, demonstrating unitarity and exploring solutions for the cosmological constant problem.

Findings

The spin-two resonance is shifted off the real axis, ensuring unitarity.

Scattering calculations confirm the theory's consistency at high energies.

The framework offers a viable UV completion for quantum gravity.

Abstract

We discuss a variation of quadratic gravity in which the gravitational interaction remains weakly coupled at all energies, but is assisted by a Yang-Mills gauge theory which becomes strong at the Planck scale. The Yang-Mills interaction is used to induce the usual Einstein-Hilbert term, which was taken to be small or absent in the original action. We study the spin-two propagator in detail, with a focus on the high mass resonance which is shifted off the real axis by the coupling to real decay channels. We calculate scattering in the $J=2$ partial wave and show explicitly that unitarity is satisfied. The theory will in general have a large cosmological constant and we study possible solutions to this, including a unimodular version of the theory. Overall, the theory satisfies our present tests for being a ultraviolet completion of quantum gravity.