Rotating Away Proton Decay in Flipped Unification

It is shown that by a simple extension of the fermion sector of flipped SU(5) models and other flipped models proton decay coming from dimension-6 operators can be suppressed by fermion mixing angles by an arbitrary amount in a natural way.Comment: 5 page

Radiative Fermion Mass Hierarchy in a Non-supersymmetric Unified Theory

In non-supersymmetric grand unified models a ``radiative fermion mass hierarchy" can be achieved in which the spectrum of quark and lepton masses is determined entirely by physics at the unification scale, with many relations following from the unified gauge symmetry, and with the masses of the lightest family arising from loops. A simple, realistic, and predictive model of this kind is presented. A "doubly lopsided" structure, known to lead to bilarge neutrino mixing, plays a crucial role in the radiative hierarchy.Comment: 14 page

Four Puzzles of Neutrino Mixing

There are four puzzling questions about by the magnitudes of neutrino mixings and mass splittings. A brief sketch is given of the various kinds of models of neutrino masses and how they answer these questions. Special attention is given to so-called "lopsided" models.Comment: 12 pages, LaTeX. Talk at NOON2001 conference, Univ. of Tokyo, Dec. 5-8, 200