A pathway to non-perturbative Quantum Affine Gravity

TL;DR

This paper proposes a non-perturbative approach to quantum gravity using a purely affine formulation, discretized on a lattice, with Monte Carlo simulations demonstrating the method in two dimensions.

Contribution

It introduces a novel non-perturbative quantization scheme for gravity based on affine connections, including a lattice discretization and Monte Carlo implementation.

Findings

The affine action is bounded below for positive cosmological constant.

A lattice partition function for affine gravity is constructed.

Proof-of-principle simulations are demonstrated in two dimensions.

Abstract

We explore a new route toward a non-perturbative quantization of gravity based on a purely affine formulation, where the affine connection is the fundamental field and the metric, when it exists, emerges as a derived quantity. Starting from the Palatini formulation of General Relativity, we recall how an equivalent Eddington-type purely affine action arises at the classical level under mild assumptions. A key feature for the non-perturbative program is that, in the pure gravity case, for a positive cosmological constant, the action is bounded below, allowing one to define a well-posed statistical ensemble of connections. We discretize this theory on a fixed hypercubic lattice and construct the corresponding partition function, including torsionful and torsionless ensembles. We provide an open C++ Monte Carlo implementation that can simulate these ensembles in arbitrary dimension, and we present proof-of-principle results in two dimensions.