Habemus Superstratum! A constructive proof of the existence of superstrata

TL;DR

This paper constructs the first explicit superstratum solutions in supergravity, demonstrating a method to generate smooth, horizonless geometries with arbitrary functions, advancing the understanding of black hole microstates in string theory.

Contribution

It provides a constructive, explicit method to generate superstratum solutions with arbitrary functions, expanding the class of known horizonless geometries in supergravity.

Findings

First explicit superstratum solutions constructed

Solutions involve arbitrary functions of two variables

Solutions are not dual to descendants of chiral primaries

Abstract

We construct the first example of a superstratum: a class of smooth horizonless supergravity solutions that are parameterized by arbitrary continuous functions of (at least) two variables and have the same charges as the supersymmetric D1-D5-P black hole. We work in Type IIB string theory on T^4 or K3 and our solutions involve a subset of fields that can be described by a six-dimensional supergravity with two tensor multiplets. The solutions can thus be constructed using a linear structure, and we give an explicit recipe to start from a superposition of modes specified by an arbitrary function of two variables and impose regularity to obtain the full horizonless solutions in closed form. We also give the precise CFT description of these solutions and show that they are not dual to descendants of chiral primaries. They are thus much more general than all the known solutions whose CFT dual is precisely understood. Hence our construction represents a substantial step toward the ultimate goal of constructing the fully generic superstratum that can account for a finite fraction of the entropy of the three-charge black hole in the regime of parameters where the classical black hole solution exists.