The arguments for searching for proton decay as advanced by GUT were so compelling that very large and sensitive experiments were built for this purpose. The evidence from these experiments along with other solar neutrino experiments are often interpreted to be signs that the neutrinos have mass and that they are oscillating from one flavour to another. If this turns out to be true, this would be in accordance with some GUTs. The strong, and the CC and NC coupling constants are converging in our present analysis of experiments. IF GUTS is true, we would expect protons to be unstable because the reactions above would violate the conservation of baryon number as well as lepton number.
Some models give longer lifetimes .
This will be summarized in a chart later. If we're going to Grand Unify, why not unify ALL the interactions including Gravity. This will Super-Kam to especially concentrate on the decay into K's . In this case there is no absolute necessity for the proton to be unstable and indeed one can construct models in which the low energy symmetry forbids proton decay within measureable limits. Super Symmetry and GUTs, G.G. Ross, p 349.