On the stability of string theory vacua

Vacuum compactifications may suffer from instabilities under small perturbations or tunnel effects; both are difficult to analyze. In this paper we consider the issue a higher-dimensional perspective. We first look at how stability works for supersymmetric vacua, where it is widely expected hold. show that nucleation of brane bubbles in type II AdS forbidden probe approximation by simple argument involving pure spinors and calibrations. then adapt familiar positive-energy theorems directly M-theory supergravity, rather than their effective lower-dimensional reductions, also showing consistently include localised sources. finally initiate an analysis these arguments might be extended non-supersymmetric vacua. M-theory, lower-derivative level, find most natural modifications fail stabilize skew-whiffed Englert