Discrete gauge symmetries in discrete MSSM-like orientifolds Original Research Article

Motivated by the necessity of discrete image symmetries in the MSSM to insure baryon stability, we study the origin of discrete gauge symmetries from open string sector imageʼs in orientifolds based on rational conformal field theory. By means of an explicit construction, we find an integral basis for the couplings of axions and image factors for all simple current MIPFs and orientifolds of all 168 Gepner models, a total of 32 990 distinct cases. We discuss how the presence of discrete symmetries surviving as a subgroup of broken imageʼs can be derived using this basis. We apply this procedure to models with MSSM chiral spectrum, concretely to all known image and image configurations with chiral bi-fundamentals, but no chiral tensors, as well as some image GUT models. We find examples of models with image (R-parity) and image symmetries that forbid certain B and/or L violating MSSM couplings. Their presence is however relatively rare, at the level of a few percent of all cases.