2,356,111 research outputs found
Checkerboard and stripe inhomogeneities in cuprates
We systematically investigate charge-ordering phases by means of a restricted
and unrestricted Gutzwiller approximation to the single-band Hubbard model with
nearest () and next-nearest neighbor hopping (). When is small,
as appropriate for , stripes are found, whereas in
compounds with larger (such as and
) checkerboard structures are favored. In
contrast to the linear doping dependence found for stripes the charge
periodicity of checkerboard textures is locked to 4 unit cells over a wide
doping range. In addition we find that checkerboard structures are favored at
surfaces.Comment: 5 pages, 3 figure
CONFINEMENT IN RELATIVISTIC POTENTIAL MODELS
In relativistic potential models of quarkonia based on a Dirac-type of
equation with a local potential there is a sharp distinction between a linear
potential V which is vector-like and one which is scalar-like: There are
normalizable solutions for a scalar-like V but not for a vector-like V. It is
pointed out that if instead one uses an equation of the no-pair type, which is
more natural from the viewpoint of field theory, this somewhat bizarre
difference disappears.Comment: LaTeX, 4 page
Black holes in extended gravity theories in Palatini formalism
We consider several physical scenarios where black holes within classical
gravity theories including and Ricci-squared corrections and formulated
\`a la Palatini can be analytically studied.Comment: 4 pages, contribution to the "Spanish Relativity Meeting in Portugal
2012 (Progress in Mathematical Relativity, Gravitation and Cosmology)",
Springer Proceedings in Mathematics (to appear
Reduction of noise in gyro outputs
Technique is described to reduce extraneous gyro output signals by using relatively inexpensive shrouds which do not increase power comsumption. Shrouds reduce noise by minimizing mass of gas spinning with rotor, reducing Reynolds number near rotor, and inducing laminar flow
Tidal interaction of a rotating 1 Msun star with a binary companion
We calculate the tidal torque on a uniformly rotating 1 Msun star at various
stages of core hydrogen burning by an orbiting companion. We apply the
`traditional approximation' and solve the radial part of the tidal
perturbations by matrix inversion of the set of finite difference equations on
a very fine grid. We have identified resonances with gravity- and
quasi-toroidal modes with up to 1000 radial nodes in the more evolved stellar
models. For low forcing frequencies we find significant tidal response due to
viscous damping of inertial modes in the convective envelope of the solar-type
star. We conclude that effects due to stellar rotation (including resonance
locking) may considerably enhance the speed of tidal evolution in solar-type
stars.Comment: accepted for publ. in A&A, 11 pages, 6 figure
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