Non-perturbative propagators in quantum gravity

TL;DR

This paper uses non-perturbative renormalisation group techniques to analyze the momentum-dependent propagators in quantum gravity, revealing mode-specific differences and enabling the derivation of curvature form factors relevant for physical observables.

Contribution

It provides the first detailed non-perturbative computation of graviton and ghost propagators' momentum dependence in quantum gravity across dimensions.

Findings

Disentangles graviton and ghost mode propagators.

Reconstructs curvature form factors from first principles.

Results are stable under gauge fixing variations.

Abstract

We employ non-perturbative renormalisation group methods to compute the full momentum dependence of propagators in quantum gravity in general dimensions. We disentangle all different graviton and Faddeev-Popov ghost modes and find qualitative differences in the momentum dependence of their propagators. This allows us to reconstruct the form factors quadratic in curvature from first principles, which enter physical observables like scattering cross sections. The results are qualitatively stable under variations of the gauge fixing choice.