Double, Double Supertube Bubble
Iosif Bena, Jan de Boer, Masaki Shigemori, Nicholas P. Warner
TL;DR
This work introduces superstrata, a novel class of completely smooth 1/8-BPS three-charge bound states that depend on functions of two variables and locally resemble 1/2-BPS objects. By double bubbling a D1–D5–P system, the authors construct a two-dimensional sheet embedded in the five-dimensional base, where each patch is 1/2-BPS with a shared 4-supersymmetry sector, enabling arbitrary two-variable embeddings. In the D1-D5-P frame these configurations yield horizonless microstate geometries that could substantially illuminate black-hole entropy in holographic contexts, potentially accounting for more entropy than traditional one-variable supertubes. The paper develops a projector-based framework to demonstrate the local existence of such configurations, sketches basis changes that clarify the supersymmetry structure, and outlines the path toward explicit supergravity realizations while acknowledging remaining theoretical challenges.
Abstract
We argue that there exists a new class of completely smooth 1/8-BPS, three-charge bound state configurations that depend upon arbitrary functions of two variables. These configurations are locally 1/2-BPS objects in that if they form an infinite flat sheet then they preserve 16 supersymmetries but even with arbitrary two-dimensional shape modes they still preserve 4 supersymmetries. They have three electric charges and can be thought of the result of two successive supertube transitions that involve adding two independent dipole moments and giving rise to the arbitrary two-dimensional shape modes. We further argue that in the D1-D5-P duality frame this construction will give rise to smooth, horizonless solutions, or microstate geometries. We expect these solutions to be extremely important in the semi-classical and holographic descriptions of black-hole entropy.
