19,206 research outputs found
Superfluid and Mott Insulating shells of bosons in harmonically confined optical lattices
Weakly interacting atomic or molecular bosons in quantum degenerate regime
and trapped in harmonically confined optical lattices, exhibit a wedding cake
structure consisting of insulating (Mott) shells. It is shown that superfluid
regions emerge between Mott shells as a result of fluctuations due to finite
hopping. It is found that the order parameter equation in the superfluid
regions is not of the Gross-Pitaeviskii type except near the insulator to
superfluid boundaries. The excitation spectra in the Mott and superfluid
regions are obtained, and it is shown that the superfluid shells posses low
energy sound modes with spatially dependent sound velocity described by a local
index of refraction directly related to the local superfluid density. Lastly,
the Berezinskii-Kosterlitz-Thouless transition and vortex-antivortex pairs are
discussed in thin (wide) superfluid shells (rings) limited by three (two)
dimensional Mott regions.Comment: 11 pages, 9 figures
Causal Structure and Birefringence in Nonlinear Electrodynamics
We investigate the causal structure of general nonlinear electrodynamics and
determine which Lagrangians generate an effective metric conformal to
Minkowski. We also proof that there is only one analytic nonlinear
electrodynamics presenting no birefringence.Comment: 11 pages, no figure
Prediction of genetic potential of common bean segregant populations for slow seed-coat darkening.
The objective of this study was to predict the genetic potential of common bean segregant populations for slow seed-coat darkening
Electromagnetic structure and weak decay of pseudoscalar mesons in a light-front QCD-inspired model
We study the scaling of the meson mass splitting and the
pseudoscalar weak decay constants with the mass of the meson, as seen in the
available experimental data. We use an effective light-front QCD-inspired
dynamical model regulated at short-distances to describe the valence component
of the pseudoscalar mesons. The experimentally known values of the mass
splittings, decay constants (from global lattice-QCD averages) and the pion
charge form factor up to 4 [GeV/c] are reasonably described by the modelComment: 27 Pages, 7 eps figures,use revtex
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