Comments on string dynamics in six dimensions Original Research Article

We discuss the singularities in the moduli space of string compactifications to six dimensions with N = 1 supersymmetry. Such singularities arise from either massless particles or non-critical tensionless strings. The points with tensionless strings are sometimes phase transition points between different phases of the theory. These results appear to connect all known N = 1 supersymmetric six-dimensional vacua.