Comparison of area spectra in loop quantum gravity

TL;DR

This paper compares two proposed area spectra in loop quantum gravity, analyzing their implications for black hole entropy and demonstrating the consistency of an equally-spaced spectrum with quasinormal modes without changing the gauge group.

Contribution

It introduces a detailed comparison of two area spectra in loop quantum gravity and shows the equally-spaced spectrum's compatibility with quasinormal modes without altering the gauge group.

Findings

Both spectra reproduce statistical quantities in the canonical ensemble.

The equally-spaced spectrum aligns with quasinormal mode connections.

The degeneracy of the area observable is bounded by C A exp(A/4).

Abstract

We compare two area spectra proposed in loop quantum gravity in different approaches to compute the entropy of the Schwarzschild black hole. We describe the black hole in general microcanonical and canonical area ensembles for these spectra. We show that in the canonical ensemble, the results for all statistical quantities for any spectrum can be reproduced by a heuristic picture of Bekenstein up to second order. For one of these spectra - the equally-spaced spectrum - in light of a proposed connection of the black hole area spectrum to the quasinormal mode spectrum and following hep-th/0304135, we present explicit calculations to argue that this spectrum is completely consistent with this connection. This follows without requiring a change in the gauge group of the spin degrees of freedom in this formalism from SU(2) to SO(3). We also show that independent of the area spectrum, the degeneracy of the area observable is bounded by $C A\exp(A/4)$, where $A$ is measured in Planck units and $C$ is a constant of order unity.