Certain early versions of grand unification based on the so-called SU(5) and minimal supersymmetric SU(5) models predict relatively short lifetimes for the proton ranging from 1028 to 1032 years, which are however excluded by IMB/Kamiokande and SuperKamiokande experiments. A class of well-motivated theories of grand unification, based on the symmetry SO(10) and supersymmetry, which have the virtue that they successfully describe the masses and mixings of all quarks and leptons including neutrinos, and which also explain the origin of an excess of matter over antimatter through a process called "leptogenesis", provide a conservative (theoretical) upper limit on proton lifetime which is within a factor of ten higher than its current empirical lower limit.This makes the discovery potential for proton decay in a next-generation detector rather high.
From a broader viewpoint, proton
decay, if found, would provide us with a unique window to view physics at truly
short distances- less than 10-30 cm., corresponding to energies greater
than 1016 GeV - a feature that can not be achieved by any other means.
It would provide the missing link of grand unification. Last but not
least, it would help ascertain our ideas about the origin of an excess of matter
over antimatter (mentioned above) that is crucial to the origin of life itself.
In this sense, and given that the predictions of a well-motivated class of grand
unified theories for proton lifetime are not far above the current empirical
limit, the need for an improved search for proton decay through a next-generation
detector seems compelling. The session would include theoretical and experimental
discussions along these lines and expose a spectrum of current thinking in the
Click Here for the Proton Decay Working Group Schedule