Moduli space of spin connections on three-dimensional homogeneous spaces

TL;DR

This paper classifies the moduli space of homogeneous spin and SU(2) connections on 3D homogeneous spaces, revealing their topological properties and implications for quantum gravity and cosmology.

Contribution

It provides a rigorous mathematical characterization of the moduli space of homogeneous spin connections relevant to quantum gravity.

Findings

Moduli spaces are finite-dimensional topological manifolds with trivial homotopy groups.

Proper formulation of the theory depends on identifying the moduli space of homogeneous spin connections.

Topological properties facilitate addressing singularities and defining measures in quantum gravity.

Abstract

In this manuscript, we aim to classify and characterize the moduli space of homogeneous spin connections and homogeneous SU(2) connections on three-dimensional Riemannian homogeneous spaces. An analysis of the topology of the associated moduli spaces reveals that they are finite-dimensional topological manifolds (possibly with boundary) possessing trivial homotopy groups. Owing to their deep connection with cosmological models in the Ashtekar-Barbero-Immirzi formulation of General Relativity, this study offers a mathematically rigorous interpretation of the Ashtekar-Barbero-Immirzi-Sen connection within a cosmological context. In particular, we show that a correct formulation of the theory relies crucially on identifying the moduli space of homogeneous spin connections, thereby emphasizing the essential role of the spin structure in ensuring consistency with the physical content of the theory. The favorable topological properties of these moduli spaces circumvent many of the usual difficulties associated with singularities and the definition of regular measures in Quantum Field Theory and Quantum Gravity. As a result, they provide a solid foundation for the rigorous implementation of quantum theory in the cosmological setting.