Fricke S-duality in CHL models

          @misc{ scivideos_PIRSA:15040124,
            doi = {10.48660/15040124},
            url = {https://pirsa.org/15040124},
            author = {Volpato, Roberto},
            keywords = {Quantum Fields and Strings},
            language = {en},
            title = {Fricke S-duality in CHL models},
            publisher = {Perimeter Institute for Theoretical Physics},
            year = {2015},
            month = {apr},
            note = {PIRSA:15040124 see, \url{https://scivideos.org/pirsa/15040124}}
          }
          

Abstract

We consider dual pairs of four dimensional heterotic/type IIA CHL models with 16 space-time supersymmetries. We provide strong evidence for the existence of an S-duality acting on the heterotic axion-dilaton by a Fricke involution S --> -1/NS, where N is the order of the orbifold symmetry. While most models are self-dual, in some cases S-duality relates the CHL model to a compactification of type IIA on an orbifold of T^6. We provide a simple criterion to determine whether a model is self-dual or not. Finally, we argue that in self-dual CHL models the lattices of electric and magnetic charges must be N-modular and verify this prediction.