532 research outputs found
Orbifold Reduction Of The Quark-Lepton Symmetric Model
We investigate the quark-lepton symmetric gauge group in five dimensions,
with the gauge symmetry broken by a combination of orbifold compactification of
the extra dimension and the Higgs mechanism. The gauge sector of the model is
investigated and contrasted with the four dimensional case. We obtain lower
bounds on the mass of the exotic gauge bosons, the inverse compactification
scale and the exotic leptons. Light neutrinos are obtained without requiring
any scale larger than a TeV. However an ultra-violet cut-off of order
GeV is required to suppress proton decay inducing non-renormalizable operators.Comment: References added to match PRD versio
Direct Improvement of Hamiltonian Lattice Gauge Theory
We demonstrate that a direct approach to improving Hamiltonian lattice gauge
theory is possible. Our approach is to correct errors in the Kogut-Susskind
Hamiltonian by incorporating additional gauge invariant terms. The coefficients
of these terms are chosen so that the order classical errors vanish. We
conclude with a brief discussion of tadpole improvement in Hamiltonian lattice
gauge theory.Comment: 9 page
Non-Boltzmann behaviour in models of interacting neutrinos
We reconsider the question of the relative importance of single particle
effects and correlations in the solvable interacting neutrino models introduced
by Friedland and Lunardini and by Bell, Rawlinson and Sawyer. We show, by an
exact calculation, that the two particle correlations are not "small", and that
they dominate the time evolution in these models, in spite of indications to
the contrary from the rate of equilibration. This result holds even after the
model in generalized from the original 2 flavor case to flavors. The
failure of the Boltzmann single particle approximation in this model is
tentatively attributed to the simplicity of the model, in particular to the
assumption that all neutrinos in the initial state are in flavor eigenstates.Comment: 8 pages, 4 figure
Persistent superfluid flow arising from the He-McKellar-Wilkens effect in molecular dipolar condensates
We show that the He-McKellar-Wilkens effect can induce a persistent flow in a
Bose-Einstein condensate of polar molecules confined in a toroidal trap, with
the dipolar interaction mediated via an electric dipole moment. For
Bose-Einstein condensates of atoms with a magnetic dipole moment, we show that
although it is theoretically possible to induce persistent flow via the
Aharonov-Casher effect, the strength of electric field required is prohibitive.
We also outline an experimental geometry tailored specifically for observing
the He-McKellar-Wilkens effect in toroidally-trapped condensates.Comment: 5 pages 2 figure
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