NUCLEON DECAY IN NONMINIMAL SUPERSYMMETRIC SO(10)

Evaluation of nucleon decay modes and branching ratios in a non-minima l supersymmetric SO(10) grand unified theory is presented. The non-min imal GUT considered is the supersymmetrised version of the 'realistic' SO(10) model originally proposed by Harvey, Reiss and Ramond, which i s realistic in that it gives acceptable charged fermion and neutrino m asses within the context of a phenomenological fit to the low-energy s tandard model inputs. Despite a complicated Higgs sector, the SO(10) 1 0 Higgs superfield mass insertion is found to be the sole contribution to the tree-level F-term governing nucleon decay. The resulting dimen sion-5 operators that mediate nucleon decay give branching ratio predi ctions parameterised by a single parameter, the ratio of the Yukawa co uplings of the 10 to the fermion generations. For parameter values cor responding to a lack of dominance of the third family self-coupling, t he dominant nucleon decay modes are p --> K+ + <(nu)over bar (mu)> and n --> K-0 + <(nu)over bar (mu)>, as expected. Further, the charged mu on decay modes are enhanced by two orders of magnitude over the standa rd minimal SUSY SU(5) predictions, thus predicting a distinct spectrum of 'visible' modes. These charged muon decay modes, along with p --> pi(+) <(nu)over bar (mu)>, and n --> pi(0) + <(nu)over bar (mu)>, whic h are moderately enhanced over the SUSY SU(5) prediction, suggest a di stinguishing fingerprint of this particular GUT model, and if nucleon decay is observed at Super-KAMIOKANDE the predicted branching ratio sp ectrum can be used to determine the validity of this 'realistic' SO(10 ) SUSY GUT model.