On Perturbative Gravity and Gauge Theory

TL;DR

This paper reviews the classical relations between gravity and gauge theories derived from string theory, their use in quantizing gravity perturbatively, and recent findings on supergravity divergences and field variables.

Contribution

It synthesizes string theory-based relations for gravity and gauge theories, and discusses their implications for supergravity divergences and perturbative quantization.

Findings

N=1 D=11 supergravity diverges.

N=8 D=4 supergravity is less divergent than thought, but diverges at five loops.

Field variables for Einstein-Hilbert Lagrangian clarify gravity-gauge theory relations.

Abstract

We review some applications of tree-level (classical) relations between gravity and gauge theory that follow from string theory. Together with $D$-dimensional unitarity, these relations can be used to perturbatively quantize gravity theories, i.e. they contain the necessary information for obtaining loop contributions. We also review recent applications of these ideas showing that N=1 D=11 supergravity diverges, and review arguments that N=8 D=4 supergravity is less divergent than previously thought, though it does appear to diverge at five loops. Finally, we describe field variables for the Einstein-Hilbert Lagrangian that help clarify the perturbative relationship between gravity and gauge theory.