Natural Doublet-Triplet Splitting in SU(N)X U(1)

It is shown that natural doublet-triplet splitting can be achieved in a relatively simple way in supersymmetric SU(N)X U(1) models with N>5.Comment: 13 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

Higgs Multiplets of the Quark-Lepton Family Group

It is shown that realistic models can be constructed in which the Standard Model Higgs field is in a non-trivial multiplet of a non-abelian family group of the quarks and leptons. It is shown that the observed quark and lepton masses and mixing angles can be fit, while the coefficients of flavor-changing four-fermion operators mediated by the extra Higgs doublets are determined in terms of only a few unknown parameters

Grand Unification without Higgs Bosons

We discuss how a model for the electroweak interactions without a Higgs could be embedded into a grand unified theory. The requirement of a non-trivial fixed point in the SU(2) sector of the weak interactions together with the requirement of the numerical unification of the gauge couplings leads to a prediction for the value of the SU(2) gauge coupling in the fixed point regime. The fixed point regime must be in the TeV region to solve the unitarity problem in the elastic scattering of W bosons. We find that the unification scale is at about 10^{14} GeV. Viable grand unified theories must thus conserve baryon number. We discuss how to build such a model without using Higgs bosons.Comment: 8 pages, to be published in the proceedings devoted to the Scientific and Human Legacy of Julius Wess, initiated by the JW2011 Workshop, August 27 - 28, 2011, Donji Milanovac, Serbi

The Cosmological Constant, False Vacua, and Axions

It is suggested that the true ground state of the world has exactly vanishing vacuum energy and that the cosmological constant that seems to have been observed is due to our region of the universe being stuck in a false vacuum, whose energy is split from the true vacuum by non-renormalizable operators that are suppressed by powers of the Planck scale. It is shown that conventional invisible axion models typically have the features needed to realize this possibility. In invisible axion models the same field and the same potential can explain both the cosmological constant (or dark energy) and the dark matter. It is also shown that the idea can be realized in non-axion models, an example of which is given having $\Lambda = M_W^7/M_{Pl}^3$, which accords well with the observed value.Comment: 17 pages, LaTe

A Single Source for All Flavor Violation

In a model proposed in 2012, all flavor mixing has a single source and is governed by a single "master matrix." This model was shown to give several predictions for quark and lepton masses and mixing angles and for mixing angles within SU(5) multiplets that are observable in proton decay. Here it is shown that the same master matrix controls the flavor-changing processes mediated by a singlet scalar that exists in the model, giving predictions for tau to mu + gamma, tau to e + gamma, and mu to e + gamma.Comment: 11 pages, no figure