Resolution of Toroidal Orbifolds in Heterotic String Theory and its Phenomenology
Michael Blaszczyk (Universität Bonn)

The compactification of heterotic string theory on toroidal orbifolds provides a promising variety of possible high energy completions of the standard model, including the concepts of supersymmetry, grand unification and extra dimensions. The simplicity of orbifolds allows for exact string calculability, however, the theory has to be away from the orbifold point in moduli space. We describe the resolution of toroidal orbifolds in the context of gauged linear sigma models which allow for access to big regions of the moduli space. The comparison of MSSM-like models at the orbifold point and in the supergravity limit reveal properties of the low energy effective action in the resolution process. The GUT breaking in done via a freely acting Wilson line which assures full blowability with a non-anomalous hypercharge.