Localized Branes and Black Holes

TL;DR

The paper addresses whether localized D- and NS-branes embedded in higher-dimensional BPS black branes yield inhomogeneous horizons or whether such inhomogeneity is suppressed as branes merge. It uses chiral null models and Green's-function techniques to analyze classical BPS solutions with localized, separated branes, showing that when the separation is taken to zero while keeping intrinsic charge distributions fixed, external multipole moments are screened and the horizon becomes translationally invariant in the internal directions. The results hold for both a three-charge black fivebrane and a four-charge black sixbrane, illustrating a no-hair–like mechanism in extremal brane systems. This suggests that highly singular inhomogeneous horizon solutions are not generic, with implications for the microstate structure and universality of smooth horizons across brane bound states, potentially extendable to other brane intersections.

Abstract

We address the delocalization of low dimensional D-branes and NS-branes when they are a part of a higher dimensional BPS black brane, and the homogeneity of the resulting horizon. We show that the effective delocalization of such branes is a classical effect that occurs when localized branes are brought together. Thus, the fact that the few known solutions with inhomogeneous horizons are highly singular need not indicate a singularity of generic D- and NS-brane states. Rather, these singular solutions are likely to be unphysical as they cannot be constructed from localized branes which are brought together from a finite separation.