Stable Nonsupersymmetric Anti–de Sitter Vacua of Massive IIA Supergravity

Stable nonsupersymmetric anti–de Sitter (AdS) vacua of string theory are widely believed not to exist. In this Letter, we analytically compute the full bosonic Kaluza-Klein spectrum around the $G_2$-invariant nonsupersymmetric ${\mathrm{AdS}}_4$ solution of massive IIA supergravity and show that it is perturbatively stable. We also provide evidence that six other nonsupersymmetric ${\mathrm{AdS}}_4$ solutions of massive IIA supergravity are perturbatively stable. Since previous studies have indicated that these AdS vacua may also be nonperturbatively stable, our findings pose a challenge to the swampland conjecture.

Figure 1

Normalized masses $M^2{L}^2$ and multiplicities for the first four KK levels of spin-0 fluctuations around the six non-supersymmetric and BF stable ${\mathrm{AdS}}_4\times S^6$ solutions of massive IIA supergravity given in Table 1. The subfigure labels (a)–(f) correspond to the ID’s of the different vacua in Table 1. The dashed red line marks the BF bound $M^2{L}^2=-\frac{9}{4}$.