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

Automated summary

This paper investigates the stability issue of vacuum compactifications from a higher-dimensional perspective. It focuses on the stability of supersymmetric vacua, analyzes the nucleation of brane bubbles in type II AdS compactifications, adapts positive-energy theorems to M-theory and type II supergravity, and discusses the inclusion of localized sources. The paper also discusses the inability to stabilize skew-whiffed and Englert vacua at the lower-derivative level in M-theory.