Custodial nonabelian gauge symmetries in realistic superstring derived models

Alon E. Faraggi
1994 Physics Letters B  
A well known problem in supersymmetric models is the presence of, lepton and baryon number violating, dimension four operators. The traditional R parity solution may not be suitable if one tries to incorporate supersymmetry into a Planck scale theory. I propose a different solution in the context of realistic string models. I show that realistic string models can give rise to custodial nonabelian gauge symmetries under which only the leptons or quarks transform. I explain how such symmetries
more » ... se in a class of free fermionic models that are based on Z_2× Z_2 orbifold with standard embedding. The custodial symmetries forbid proton decay from dimension four operators while allowing R parity violation.
doi:10.1016/0370-2693(94)90636-x fatcat:yeydtjptuzhczaw42qpeatrl3q