Superheavy particles,sin2θW, and proton lifetime

Abstract

The maximum possible increase in the grand unification mass, and the corresponding changes in ${{sin}^{2}\ensuremath{\theta}}_{W}$ and proton lifetime, due to the presence of superheavy particles with masses somewhat smaller than the unification mass, are estimated. We consider grand unified theories (GUT's) with an invisible axion and supersymmetric GUT's based, in both cases, on the gauge groups SU(5) and SO(10).