Conformal Symmetry Breaking and Thermodynamics of Near-Extremal Black Holes

TL;DR

This paper demonstrates that the conformal symmetry breaking scale in near-extremal black holes coincides with the thermodynamic mass gap, linking gravitational backreaction to thermodynamic breakdown and extending the analysis to complex models.

Contribution

It establishes the equivalence of conformal symmetry breaking and the thermodynamic mass gap in near-extremal black holes, and develops a method to analyze more complex models with extremal throats.

Findings

The symmetry breaking scale matches the thermodynamic mass gap.

The original model captures universal near-horizon physics at tree level.

The analysis extends to more complicated extremal throat models.

Abstract

It has been argued recently by Almheiri and Polchinski that the near-horizon conformal symmetry of extremal black holes must be broken due to gravitational backreaction at an IR scale linear in $G_N$. In this paper, we show that this scale coincides with the so-called `thermodynamic mass gap' of near-extremal black holes, a scale which signals the breakdown of their thermodynamic description. We also develop a method which extends the analysis of Almheiri and Polchinski to more complicated models with extremal throats by studying the bulk linearized quantum field theory. Moreover, we show how their original model correctly captures the universal physics of the near-horizon region of near-extremal black holes at tree level, and conclude that this equivalence of the conformal breaking and mass gap scale is general.