Proton decay in the semi-simple unification

Semi-simple unification is one of models which naturally solve two difficulties in the supersymmetric grand unification theory: doublet–triplet splitting problem and suppression of dimension 5 proton decay. We analyzed the dimension 6 proton decay of this model using perturbative analysis at the next-to-leading order. The life time of proton is 3×1034–1035 years for wide range of SUSY breaking parameters, and there is an intriguing possibility of observing proton decay signals in the next-generation water Čerenkov detectors such as Hyper-Kamiokande and TITAND. Several uncertainties in this prediction are also discussed.