6,204 research outputs found
Yang-Baxter algebra and generation of quantum integrable models
An operator deformed quantum algebra is discovered exploiting the quantum
Yang-Baxter equation with trigonometric R-matrix. This novel Hopf algebra along
with its limit appear to be the most general Yang-Baxter algebra
underlying quantum integrable systems. Three different directions of
application of this algebra in integrable systems depending on different sets
of values of deforming operators are identified. Fixed values on the whole
lattice yield subalgebras linked to standard quantum integrable models, while
the associated Lax operators generate and classify them in an unified way.
Variable values construct a new series of quantum integrable inhomogeneous
models. Fixed but different values at different lattice sites can produce a
novel class of integrable hybrid models including integrable matter-radiation
models and quantum field models with defects, in particular, a new quantum
integrable sine-Gordon model with defect.Comment: 13 pages, revised and bit expanded with additional explanations,
accepted for publication in Theor. Math. Phy
Electron transport and thermoelectric properties of layered perovskite LaBaCo2O5.5
We have investigated the systematic transport properties of the layered
112-type cobaltite LaBaCo2O5.5 by means of electrical resistivity,
magnetoresistance, electroresistance and thermoelectric measurements in various
conditions. In order to understand the complex conduction mechanism of
LaBaCo2O5.5, the transport data have been analyzed using different theoretical
models. The system shows semiconductor-semiconductor like transition (TSC)
around 326K, corresponding to ferromagnetic transition and in the low
temperature region resistivity data follows the Motts variable range hopping
model. Interestingly, near and below the room temperature this compound depicts
significant change in electro- and magnetoresistance behavior, the latter one
is noteworthy near the magnetic phase boundary. The temperature dependence of
thermopower, S(T), exhibits p-type polaronic conductivity in the temperature
range of 60-320K and reaches a maximum value of 303 uV/K (at 120K). In the low
temperature AFM region, the unusual S(T) behavior, generally observed for the
cobaltite series LnBaCo2O5.5 (Ln = Rare Earth), is explained by the electron
magnon scattering mechanism as previously described for perovskite manganites.Comment: 18 pages including fig
Green-Kubo formula for heat conduction in open systems
We obtain an exact Green-Kubo type linear response result for the heat
current in an open system. The result is derived for classical Hamiltonian
systems coupled to heat baths. Both lattice models and fluid systems are
studied and several commonly used implementations of heat baths, stochastic as
well as deterministic, are considered. The results are valid in arbitrary
dimensions and for any system sizes. Our results are useful for obtaining the
linear response transport properties of mesoscopic systems. Also we point out
that for systems with anomalous heat transport, as is the case in
low-dimensional systems, the use of the standard Green-Kubo formula is
problematic and the open system formula should be used.Comment: 4 page
Quantum integrable multi atom matter-radiation models with and without rotating wave approximation
New integrable multi-atom matter-radiation models with and without rotating
wave approximation (RWA) are constructed and exactly solved through algebraic
Bethe ansatz. The models with RWA are generated through ancestor model approach
in an unified way. The rational case yields the standard type of
matter-radiaton models, while the trigonometric case corresponds to their
q-deformations. The models without RWA are obtained from the elliptic case at
the Gaudin and high spin limit.Comment: 9 pages, no figure, talk presented in int. conf. NEEDS04 (Gallipoli,
Italy, July 2004
The Hyperbolic Heisenberg and Sigma Models in (1+1)-dimensions
Hyperbolic versions of the integrable (1+1)-dimensional Heisenberg
Ferromagnet and sigma models are discussed in the context of topological
solutions classifiable by an integer `winding number'. Some explicit solutions
are presented and the existence of certain classes of such winding solutions
examined.Comment: 13 pages, 1 figure, Latex, personal style file included tensind.sty,
Proof in section 3 altered, no changes to conclusion
Ring-shaped exact Hopf solitons
The existence of ring-like structures in exact hopfion solutions is shown.Comment: version accepted for publication in JMP, includes symmetry
transformation for finite paramete
Collisionless energy absorption in the short-pulse intense laser-cluster interaction
In a previous Letter [Phys. Rev. Lett. 96, 123401 (2006)] we have shown by
means of three-dimensional particle-in-cell simulations and a simple
rigid-sphere model that nonlinear resonance absorption is the dominant
collisionless absorption mechanism in the intense, short-pulse laser cluster
interaction. In this paper we present a more detailed account of the matter. In
particular we show that the absorption efficiency is almost independent of the
laser polarization. In the rigid-sphere model, the absorbed energy increases by
many orders of magnitude at a certain threshold laser intensity. The
particle-in-cell results display maximum fractional absorption around the same
intensity. We calculate the threshold intensity and show that it is
underestimated by the common over-barrier ionization estimate.Comment: 12 pages, 13 figures, RevTeX
A Class of Exact Solutions of the Faddeev Model
A class of exact solutions of the Faddeev model, that is, the modified SO(3)
nonlinear sigma model with the Skyrme term, is obtained in the four dimensional
Minkowskian spacetime. The solutions are interpreted as the isothermal
coordinates of a Riemannian surface. One special solution of the static vortex
type is investigated numerically. It is also shown that the Faddeev model is
equivalent to the mesonic sector of the SU(2) Skyrme model where the baryon
number current vanishes.Comment: 20 pages, 7 figures, refs. adde
Negative Even Grade mKdV Hierarchy and its Soliton Solutions
In this paper we provide an algebraic construction for the negative even mKdV
hierarchy which gives rise to time evolutions associated to even graded Lie
algebraic structure. We propose a modification of the dressing method, in order
to incorporate a non-trivial vacuum configuration and construct a deformed
vertex operator for , that enable us to obtain explicit and
systematic solutions for the whole negative even grade equations
Algebraic approach in unifying quantum integrable models
A novel algebra underlying integrable systems is shown to generate and unify
a large class of quantum integrable models with given -matrix, through
reductions of an ancestor Lax operator and its different realizations. Along
with known discrete and field models a new class of inhomogeneous and impurity
models are obtained.Comment: Revtex, 6 pages, no figure, revised version to be published in Phys.
Rev. Lett., 199
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