E6 interpretation of an e+e-γγE/T event

The lowest-dimensional representation of the group E6 contains both the standard quarks and leptons and a set of exotic quarks and leptons whose decays can involve a series of chains ending in radiative decay of one light neutrino species into another. An example is given based on the decomposition E6→ SU(2)IxSU(6), where SU(2)I is an open-quotes inertclose quotes subgroup whose gauge bosons WI(±) and ZI are all electromagnetically neutral, while SU(6) contains the conventional SU(5) grand-unified group. The possibility is explored that such a chain is responsible for an event observed by the Collider Detector at Fermilab involving the production in proton-antiproton collisions at Ec.m.=1.8 TeV of an electron-positron pair, two photons, and missing energy (e+e-γγE/T). copyright 1997 The American Physical Society