Euclidian 4d quantum gravity with a non-trivial measure term

TL;DR

This paper investigates 4d Euclidean quantum gravity using dynamical triangulations, adding a measure term to explore phase structure, but finds no suitable second order transition for continuum physics.

Contribution

It introduces a measure term as a generalized higher curvature term in 4d quantum gravity and maps the phase diagram, revealing the absence of a second order transition.

Findings

First order phase transition observed

No second order transition point found

Crinkled phase lacks continuum physics interpretation

Abstract

We explore an extended coupling constant space of 4d regularized Euclidean quantum gravity, defined via the formalism of dynamical triangulations. We add a measure term which can also serve as a generalized higher curvature term and determine the phase diagram and the geometries dominating in the various regions. A first order phase transition line is observed, but no second order transition point is located. As a consequence we cannot attribute any continuum physics interpretation to the so-called crinkled phase of 4d dynamical triangulations.