Quasilocal Energy for Spin-net Gravity

TL;DR

This paper quantizes the quasilocal energy in a gravitational system with boundary using spin network techniques, resulting in a gauge-invariant operator with a computed spectrum and implications for quantum gravity.

Contribution

It introduces a gauge-invariant quantization of the boundary Hamiltonian as a quasilocal energy operator within spin-net gravity, with spectrum analysis and alternative formulations.

Findings

The quasilocal energy operator is well-defined and gauge-invariant.

The spectrum of the operator is explicitly computed.

An alternative operator form with correct classical limit is proposed.

Abstract

The Hamiltonian of a gravitational system defined in a region with boundary is quantized. The classical Hamiltonian, and starting point for the regularization, is required by functional differentiablity of the Hamiltonian constraint. The boundary term is the quasilocal energy of the system and becomes the ADM mass in asymptopia. The quantization is carried out within the framework of canonical quantization using spin networks. The result is a gauge invariant, well-defined operator on the Hilbert space induced from the state space on the whole spatial manifold. The spectrum is computed. An alternate form of the operator, with the correct naive classical limit, but requiring a restriction on the Hilbert space, is also defined. Comparison with earlier work and several consequences are briefly explored.