IMPLICATIONS OF SUPERSYMMETRIC MODELS WITH NATURAL R-PARITY CONSERVATION

In the minimal supersymmetric standard model, the conservation of R pa rity is phenomenologically desirable, but is ad hoc in the sense that it is not required for the internal consistency of the theory. However , if B-L is gauged at very high energies, R parity will be conserved a utomatically and exactly, provided only that all order parameters carr y even integer values of 3(B-L). We propose a minimal extension of the supersymmetric standard model in which R-parity conservation arises n aturally in this way. This approach predicts the existence of a very w eakly coupled, neutral chiral supermultiplet of particles with electro weak-scale masses and lifetimes which may be cosmologically interestin g. Neutrino masses arise via an intermediate-scale seesaw mechanism, a nd a solution to the mu problem is naturally incorporated. The apparen t unification of gauge couplings at high energies is shown to be prese rved in this approach. We also discuss a next-to-minimal extension, wh ich predicts a pair of electroweak-scale chiral supermultiplets with e lectric charge 2.