Bosonisation and BTZ Black Hole Microstates

TL;DR

This paper constructs BTZ black hole microstates using bosonization of boundary fermions in AdS3 gravity, linking microstate degeneracy to classical entropy through a novel fermionic representation.

Contribution

It introduces a fermionic bosonization approach to model BTZ microstates, connecting boundary dynamics to bulk black hole entropy.

Findings

Microstates correspond to Young diagrams of U(∞) representations.

Microstate degeneracy logarithm matches BTZ entropy.

Boundary fermion states encode black hole microstates.

Abstract

When the boundary dynamics of \(AdS_3\) gravity is governed by the collective field theory Hamiltonian proposed by Jevicki and Sakita, its asymptotic symmetry algebra becomes the centerless \(U(1)\) Kac-Moody algebra. We quantize this system using the quantum bosonization of relativistic free fermions and relate these to the dynamical fields of \(AdS_3\) gravity. This leads to a correspondence where different bulk configurations correspond to distinct states (particle-hole pair excitations) in the fermionic Hilbert space. This mapping allows us to construct BTZ black hole microstates, represented by Young diagrams of irreducible \(U(\infty)\) representations. Notably, the logarithm of the microstate degeneracy exactly reproduces the classical entropy of the BTZ black hole.