6,413 research outputs found
Symmetries of differential-difference dynamical systems in a two-dimensional lattice
Classification of differential-difference equation of the form
are considered
according to their Lie point symmetry groups. The set represents the
point and its six nearest neighbors in a two-dimensional triangular
lattice. It is shown that the symmetry group can be at most 12-dimensional for
abelian symmetry algebras and 13-dimensional for nonsolvable symmetry algebras.Comment: 24 pages, 1 figur
Photo-excited zero-resistance states in the GaAs/AlGaAs system
The microwave-excited high mobility two-dimensional electron system exhibits,
at liquid helium temperatures, vanishing resistance in the vicinity of , where , m is an
effective mass, e is the charge, and \textit{f} is the microwave frequency.
Here, we summarize some experimental results.Comment: 7 color figures, 5 page
Lie point symmetries of difference equations and lattices
A method is presented for finding the Lie point symmetry transformations
acting simultaneously on difference equations and lattices, while leaving the
solution set of the corresponding difference scheme invariant. The method is
applied to several examples. The found symmetry groups are used to obtain
particular solutions of differential-difference equations
Continuous Symmetries of Difference Equations
Lie group theory was originally created more than 100 years ago as a tool for
solving ordinary and partial differential equations. In this article we review
the results of a much more recent program: the use of Lie groups to study
difference equations. We show that the mismatch between continuous symmetries
and discrete equations can be resolved in at least two manners. One is to use
generalized symmetries acting on solutions of difference equations, but leaving
the lattice invariant. The other is to restrict to point symmetries, but to
allow them to also transform the lattice.Comment: Review articl
Discrete derivatives and symmetries of difference equations
We show on the example of the discrete heat equation that for any given
discrete derivative we can construct a nontrivial Leibniz rule suitable to find
the symmetries of discrete equations. In this way we obtain a symmetry Lie
algebra, defined in terms of shift operators, isomorphic to that of the
continuous heat equation.Comment: submitted to J.Phys. A 10 Latex page
Electronic Raman scattering of Tl-2223 and the symmetry of the supercon- ducting gap
Single crystalline Tl2Ba2Ca2Cu3O10 was studied using electronic Raman
scattering. The renormalization of the scattering continuum was investigated as
a function of the scattering geometry to determine the superconducting energy
gap 2Delta(k). The A1g- and B2g-symmetry component show a linear frequency
behaviour of the scattering intensity with a peak related to the energy gap,
while the B1g-symmetry component shows a characteristic behaviour at higher
frequencies. The observed frequency dependencies are consistent with a
dx^2-y^2-wave symmetry of the gap and yield a ratio of 2Delta/k_BT_c=7.4. With
the polarization of the scattered and incident light either parallel or
perpendicular to the CuO2-planes a strong anisotropy due to the layered
structure was detected, which indicates an almost 2 dimensional behaviour of
this system.Comment: 2 pages, Postscript-file including 2 figures. Accepted for
publication in the Proceedings of the M^2SHTSC IV Conference, Grenoble
(France), 5-9 July 1994. Proceedings to be published in Physica C. Contact
address: [email protected]
Kinetic Antiferromagnetism in the Triangular Lattice
We show that the motion of a single hole in the infinite Hubbard model
with frustrated hopping leads to weak metallic antiferromagnetism of kinetic
origin. An intimate relationship is demonstrated between the simplest versions
of this problem in 1 and 2 dimensions, and two of the most subtle many body
problems, namely the Heisenberg Bethe ring in 1-d and the 2-dimensional
triangular lattice Heisenberg antiferromagnet.Comment: 10 pages, 2 figures, 5 supplementary figures; Figures fixe
Infinitely many symmetries and conservation laws for quad-graph equations via the Gardner method
The application of the Gardner method for generation of conservation laws to
all the ABS equations is considered. It is shown that all the necessary
information for the application of the Gardner method, namely B\"acklund
transformations and initial conservation laws, follow from the multidimensional
consistency of ABS equations. We also apply the Gardner method to an asymmetric
equation which is not included in the ABS classification. An analog of the
Gardner method for generation of symmetries is developed and applied to
discrete KdV. It can also be applied to all the other ABS equations
The lattice Schwarzian KdV equation and its symmetries
In this paper we present a set of results on the symmetries of the lattice
Schwarzian Korteweg-de Vries (lSKdV) equation. We construct the Lie point
symmetries and, using its associated spectral problem, an infinite sequence of
generalized symmetries and master symmetries. We finally show that we can use
master symmetries of the lSKdV equation to construct non-autonomous
non-integrable generalized symmetries.Comment: 11 pages, no figures. Submitted to Jour. Phys. A, Special Issue SIDE
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