Nonperturbative Stability of Supergravity and Superstring Vacua

We investigate the possibility of false vacuum decay in $N=1$ supergravity theories. By establishing a Bogomol'nyi bound for the energy density stored in the domain wall of the $O(4)$ invariant bubble, we show that supersymmetric vacua remain absolutely stable against false vacuum decay into another supersymmetric vacuum. This conforms with and completes the previous perturbative analysis of Weinberg. Implications for dynamical supersymmetry breaking and decompactification instabilities in superstring theory are discussed. In addition, we show that there are no compact static spherical domain walls.