New Spin Foam Models of Quantum Gravity

TL;DR

This paper reviews existing spin foam models of quantum gravity, introduces two new models derived from direct quantization of General Relativity, and discusses their advantages over previous models.

Contribution

It presents two novel spin foam models that address limitations of earlier Barrett-Crane models, advancing the quantization of General Relativity.

Findings

New spin foam model for embedded spin networks in loop quantum gravity

Spin foam model based on tetrad integration in Palatini action

Models avoid drawbacks of Barrett-Crane models

Abstract

We give a brief and a critical review of the Barret-Crane spin foam models of quantum gravity. Then we describe two new spin foam models which are obtained by direct quantization of General Relativity and do not have some of the drawbacks of the Barret-Crane models. These are the model of spin foam invariants for the embedded spin networks in loop quantum gravity and the spin foam model based on the integration of the tetrads in the path integral for the Palatini action.