GLUEBALL MEDIATED DECAY OF MASSIVE NEUTRINOS IN QUARK-LEPTON SYMMETRIC MODELS

Abstract

The mysterious similarity of quarks and leptons may be invoked to motivate the hypothesis of an exact discrete symmetry between the quarks and the leptons which is broken spontaneously. This hypothesis predicts the existence of heavy bound states and light glueballs associated with an unbroken SU(2)′ gauge symmetry. We show that some of these bound states can mix significantly with the ordinary leptons. An interesting consequence of this mixing is that a massive neutrino can decay surprisingly quickly via real or virtual SU(2)′ glueball emission. Hence, we argue that massive neutrinos in generic quark-lepton symmetric models may decay fast enough to be consistent with the energy density bound in the standard big bang model of cosmology.