Black-holes, Duality and Supersymmetry

TL;DR

This paper investigates how duality transformations affect rotating black holes in string theory, revealing that they do not resolve the discrepancy between supersymmetry and extremality bounds, with superradiance providing a physical explanation.

Contribution

It demonstrates that duality transformations leave the Bogomolnyi bound invariant for certain black hole backgrounds, explaining the persistent discrepancy with extremality bounds.

Findings

Duality transformations do not constrain angular momentum to reconcile bounds.

The Bogomolnyi bound remains invariant under specific dualities.

Superradiance explains the discrepancy between bounds.

Abstract

In order to study the discrepancy between the supersymmetry bound and the extremality bound for rotating black holes, the effect of duality transformations on the class of stationary and axially symmetric string backgrounds, called the TNbh, is considerd. It is shown that the Bogomolnyi bound is invariant under those duality transformations that transform the TNbh into itself, meaning that duality does not constrain the angular momentum in such a way as to reconcile the aforementioned bounds. A physical reason for the existence of the discrepancy is given in terms of superradiance.