The Semiclassical Limit of Causal Dynamical Triangulations

TL;DR

This paper investigates the semiclassical limit of causal dynamical triangulations (CDT) in quantum gravity, confirming a de Sitter universe structure and exploring discretization effects and higher-order curvature terms.

Contribution

It provides a detailed nonperturbative analysis of the semiclassical limit in CDT, including a new method for fixing total four-volume in simulations.

Findings

Confirmation of de Sitter universe structure in CDT

Identification of short-distance discretization effects

First detailed investigation of higher-order curvature terms

Abstract

Previous work has shown that the macroscopic structure of the theory of quantum gravity defined by causal dynamical triangulations (CDT) is compatible with that of a de Sitter universe. After emphasizing the strictly nonperturbative nature of this semiclassical limit we present a detailed study of the three-volume data, which allows us to re-confirm the de Sitter structure, exhibit short-distance discretization effects, and make a first detailed investigation of the presence of higher-order curvature terms in the effective action for the scale factor. Technically, we make use of a novel way of fixing the total four-volume in the simulations.