Continuous degeneracy of non-supersymmetric vacua
  In global supersymmetric Wess-Zumino models with minimal K\"ahler potentials, F-type supersymmetry breaking always yields instability or continuous degeneracy of non-supersymmetric vacua. As a generalization of the original O'Raifeartaigh's result, the existence of instability or degeneracy is true to any higher order corrections at tree level for models even with non-renormalizable superpotentials. The degeneracy generically coincides the R-axion direction under some assumptions of R-charge assignment, but generally requires neither R-symmetries nor any assumption of generic superpotentials. The result also confirms the well-known fact that tree level supersymmetry breaking is a very rare occurrence in global supersymmetric theories with minimal K\"ahler potentials. The implication for effective field theory method in the landscape is discussed and we point out that choosing models with minimal K\"ahler potentials may result in unexpected answers to the vacuum statistics. Supergravity theories or theories with non-minimal K\"ahler potentials in general do not suffer from the existence of instability or degeneracy. But very strong gauge dynamics or small compactification dimension reduces the K\"ahler potential from non-minimal to minimal, and gravity decoupling limit reduces supergravity to global supersymmetry. Instability or degeneracy may appear in these limits. Away from these limits, a large number of non-SUSY vacua may still be found in an intermediate region. 
Zheng Sun