14,633 research outputs found
New Type of Vector Gauge Theory from Noncommutative Geometry
Using the formalism of noncommutative geometric gauge theory based on the
superconnection concept, we construct a new type of vector gauge theory
possessing a shift-like symmetry and the usual gauge symmetry. The new
shift-like symmetry is due to the matrix derivative of the noncommutative
geometric gauge theory, and this gives rise to a mass term for the vector field
without introducing the Higgs field. This construction becomes possible by
using a constant one form even matrix for the matrix derivative, for which only
constant zero form odd matrices have been used so far. The fermionic action in
this formalism is also constructed and discussed.Comment: 12 pages, LaTeX file, to appear in Phys. Lett.
Effects of field modulation on Aharonov-Bohm cages in a two-dimensional bipartite periodic lattice
We study the effects of field modulation on the energy spectrum of an
electron in a two-dimensional bipartite periodic lattice subject to a magnetic
field. Dependence of the energy spectrum on both the period and the strength of
field modulation is discussed in detail. Our main finding is that introducing
field modulation drastically changes the energy spectrum and the localization
properties of the system appearing in the absence of field modulation; the
degeneracies induced by a uniform magnetic field are broken and the resultant
energy spectrum shows a dispersive band structure, indicating that most of
Aharonov-Bohm cages become unbounded. The effects of field modulation on the
superconducting transition temperature and the critical current in a wire
network with the same geometry are also discussed.Comment: 9 figures; To appear on Phys. Rev. B 62 (15 August, 2000
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