Brane polarization is no cure for tachyons

TL;DR

This paper demonstrates that brane polarization does not resolve tachyonic instabilities in anti-brane configurations, revealing persistent instabilities even after polarization into five-branes.

Contribution

It shows that brane polarization cannot cure tachyons and that polarized shells remain unstable in certain regimes, challenging previous assumptions.

Findings

Polarized branes with tachyons are unstable.

Tachyonic instabilities persist despite polarization.

Anti-D3 branes in the Klebanov-Strassler background are unstable.

Abstract

Anti-M2 and anti-D3 branes placed in regions with charges dissolved in fluxes have a tachyon in their near-horizon region, which causes these branes to repel each other. If the branes are on the Coulomb branch this tachyon gives rise to a runaway behavior, but when the branes are polarized into five-branes this tachyon only appears to lower the energy of the polarized branes, without affecting its stability. We analyze brane polarization in the presence of a brane-brane-repelling tachyon and show that when the branes are polarized along the direction of the tachyon the polarized shell is unstable. This implies that tachyons cannot be cured by brane polarization and indicates that, at least in a certain regime of parameters, anti-D3 branes polarized into NS5 branes at the bottom of the Klebanov-Strassler solution have an instability.