Nucleon decay in supergravity unified theories

Abstract

A general analysis of nucleon decay in supergravity unified models is given including the full set of W-gaugino, gluino, and Z-gaugino dressing diagrams (with gauge as well as Yukawa interactions at vertices) of LLLL and RRRR dimension-five operators generated by Higgs-triplet exchange. The analysis is carried out within the framework of a model-independent formalism of SU(2)×U(1) breaking in supergravity models. Full symmetry-breaking effects on the vertices as well as all the allowed mass splittings of the supersymmetric particles that enter the dressing diagrams (i.e., W gauginos, Z gauginos, scalar quarks, and scalar leptons) are included. L-R mixing effects on scalar-quark–scalar-lepton masses, which are quite significant for the third generation for a heavy top quark, are also taken into account. Applications of the general analysis are made and it is shown that modification of supersymmetry predictions of nucleon decay can arise due to the inclusion of the new effects. It is shown specifically that ν¯π modes dominate nucleon decay in certain domains of the parameter space rather than ν¯K modes as is conventionally the case.