Supersymmetry Breaking by Metastable vacua

[[abstract]]We study supersymmetry breaking by metastable vacua. First we investigate the general O'Raiferataigh models. These models use a non-zero F-term to break SUSY. We show how an additional small interaction term would generate a SUSY vacuum and a metastable SUSY breaking state. The general features are studied when we extend the pseudo-potential to a more general form and we find some very unusual moduli structures in certain interesting choices. Then we consider the work of K.R. Dienes and B. Thomas (2008). In this latter model, both D-term and F-term are present in the scalar potential. Hence it offers a very rich vacuum structure including several unstable states, a SUSY vacuum and a metastable SUSY breaking state. We generalize the model by various simpli?cations and demonstrate how the crucial features could be preserved and even improved upon. In both of the above cases, the vacuum structure can be determined perturbatively at tree level. This is a huge advantage over strong interacting SUSY breaking models. The tunneling between the metastable state and the real vacuum can be calculated. We study some physical implications of these models.