Giant Tachyons in the Landscape

TL;DR

The paper addresses whether anti-D3 branes placed in the Klebanov-Strassler background can yield metastable de Sitter vacua. It employs a non-supersymmetric Polchinski-Strassler analysis, aided by smeared solutions, to derive the polarization potentials of localized anti-D3 branes into various 5-brane shells and to track UV-driven deformations of the dual gauge theory. The central result is a universal tachyonic instability: in NS5 and oblique polarization channels, there exists a direction with negative quadratic term, implying repulsion and instability of the polarized configurations. This undermines the viability of anti-D3 uplift as a mechanism for stable de Sitter vacua in KS and aligns with broader expectations about instabilities in non-supersymmetric brane solutions. The work suggests that such tachyonic behavior may be intrinsic to branes in flux backgrounds and motivates further probing across duality frames and parameter regimes.

Abstract

We study the dynamics of localized and fully backreacting anti-D3 branes at the tip of the Klebanov-Strassler geometry. We use a non-supersymmetric version of the Polchinski-Strassler analysis to compute the potential for anti-D3 branes to polarize into all kinds of five-brane shells in all possible directions. We find that generically there is a direction along which the brane-brane interaction is repulsive, which implies that anti-D3 branes are tachyonic. Hence, even though anti-D3 branes can polarize into five-branes, the solution will most likely be unstable. This indicates that anti-D3 brane uplift may not result in stable de Sitter vacua.

Figures (3)

• Figure 1: The backreaction of localized anti-D3 branes creates an $AdS$ throat at the North Pole of the 3-sphere at the bottom of the deformed conifold. The imaginary self-dual (ISD) flux leaking into the throat becomes singular in the deep IR. We investigate the possible resolutions of this singularity by the polarization of the anti-D3 branes into D5, NS5 and other $(p,q)$ 5-branes.
• Figure 2: The "gluing surface" between the near-$\overline{D3}$ solution and the KS background is different for localized (left) and smeared sources (center). On the other hand, for a large Schwarzschild radius (right), the surface is once again $SU(2) \times SU(2)$ invariant and the mass parameters are independent of the anti-branes position at the tip.
• Figure 3: For concentric 2-sphere shells (left) the polarization potential for a single shell is independent of the others. However when the branes are smeared inside the polarization plane and the 2-spheres intersect (center) there are new massless degrees of freedom that are not included in the DBI action and which cause the spheres to merge into cylindrical shells (right).