On Supersymmetry Breaking in String Theory and its Realization in Brane Worlds

We use string duality to describe instanton induced spontaneous supersymmetry breaking in string compactifications with additional background fields. Dynamical supersymmetry breaking by space-time instantons in the heterotic string theory is mapped to a tree level breaking in the type II string which can be explicitly calculated by geometric methods. It is argued that the instanton corrections resurrect the no-go theorem on partial supersymmetry breaking. The point particle limit describes the non-perturbative scalar potential of a SYM theory localized on a hypersurface of space-time. The N=0 vacuum displays condensation of magnetic monopoles and confinement. The supersymmetry breaking scale is determined by $M_{str}$, which can be in the TeV range, and the geometry transverse to the gauge theory.