Bubble instability of mIIA on AdS₄ × S⁶

We consider compactifications of massive IIA supergravity on a six-sphere. This setup is known to give rise to non-supersymmetric AdS₄ vacua preserving SO(7) as well as G₂ residual symmetry. Both solutions have a round S⁶ metric and are supported by the Romans’ mass and internal F₆ flux. While the SO(7) invariant vacuum is known to be perturbatively unstable, the G₂ invariant one has been found to have a fully stable Kaluza-Klein spectrum. Moreover, it has been shown to be protected against brane-jet instabilities. Motivated by these results, we study possible bubbling solutions connected to the G₂ vacuum, representing non-perturbative instabilities of the latter. We indeed find an instability channel represented by the nucleation of a bubble of nothing dressed up with a homogeneous D2 brane charge distribution in the internal space. Our solution generalizes to the case where S⁶ is replaced by any six-dimensional nearly-Kähler manifold.