U(1)' solution to the mu-problem and the proton decay problem in supersymmetry without R-parity

摘要

The Minimal Supersymmetric Standard Model (MSSM) is plagued by two majorfine-tuning problems: the mu-problem and the proton decay problem. We present asimultaneous solution to both problems within the framework of a U(1)'-extendedMSSM (UMSSM), without requiring R-parity conservation. We identify severalclasses of phenomenologically viable models and provide specific examples ofU(1)' charge assignments. Our models generically contain either lepton numberviolating or baryon number violating renormalizable interactions, whosecoexistence is nevertheless automatically forbidden by the new U(1)' gaugesymmetry. The U(1)' symmetry also prohibits the potentially dangerous and oftenignored higher-dimensional proton decay operators such as QQQL and UUDE whichare still allowed by R-parity. Thus, under minimal assumptions, we show thatonce the mu-problem is solved, the proton is sufficiently stable, even in thepresence of a minimum set of exotics fields, as required for anomalycancellation. Our models provide impetus for pursuing the colliderphenomenology of R-parity violation within the UMSSM framework.