Moulting Black Holes

TL;DR

This paper discovers new supersymmetric phases of the D1-D5 conformal field theory with higher entropy than known states, and identifies bulk configurations with more entropy than traditional black holes, challenging previous assumptions about black hole existence in certain parameter ranges.

Contribution

It introduces novel supersymmetric phases and bulk configurations with higher entropy, revealing black hole-like objects in previously thought black hole-free regions.

Findings

Identifies supersymmetric phases with non-Cardy-like entropy.

Finds bulk BPS configurations exceeding BMPV black hole entropy.

Shows some CFT states are lifted at strong coupling.

Abstract

We find a family of novel supersymmetric phases of the D1-D5 CFT, which in certain ranges of charges have more entropy than all known ensembles. We also find bulk BPS configurations that exist in the same range of parameters as these phases, and have more entropy than a BMPV black hole; they can be thought of as coming from a BMPV black hole shedding a "hair" condensate outside of the horizon. The entropy of the bulk configurations is smaller than that of the CFT phases, which indicates that some of the CFT states are lifted at strong coupling. Neither the bulk nor the boundary phases are captured by the elliptic genus, which makes the coincidence of the phase boundaries particularly remarkable. Our configurations are supersymmetric, have non-Cardy-like entropy, and are the first instance of a black hole entropy enigma with a controlled CFT dual. Furthermore, contrary to common lore, these objects exist in a region of parameter space (between the "cosmic censorship bound" and the "unitarity bound") where no black holes were thought to exist.