Antibranes don't go black

TL;DR

This paper proves analytically that antibranes in flux backgrounds cannot be cloaked by horizons, implying they are inherently unstable and tend to annihilate with the flux, challenging their physical viability.

Contribution

It provides an analytic proof that all codimension-three antibrane solutions cannot be hidden behind horizons, confirming their inherent instability.

Findings

Antibranes cannot be cloaked by horizons in flux backgrounds.

Black branes must have charges matching the background flux sign.

Antibranes in positive flux backgrounds immediately annihilate.

Abstract

When D-branes are inserted in flux backgrounds of opposite charge, the resulting solution has a certain singularity in the fluxes. Recently it has been argued, using numerical solutions, that for anti-D3 branes in the Klebanov-Strassler background these singularities cannot be cloaked by a horizon, which strongly suggests they are not physical. In this note we provide an analytic proof that the singularity of all codimension-three antibrane solutions (such as anti-D6 branes in massive type IIA supergravity or anti-D3 branes smeared on the T^3 of R^3xT^3 with fluxes) cannot be hidden behind a horizon, and that the charge of black branes with smooth event horizons must have the same sign as the charge of the flux background. Our result indicates that infinitesimally blackening the antibranes immediately triggers brane-flux annihilation, and strengthens the intuition that antibranes placed in flux with positive charge immediately annihilate against it.