4,470 research outputs found
Lunin-Maldacena backgrounds from the classical Yang-Baxter equation -- Towards the gravity/CYBE correspondence
We consider \gamma-deformations of the AdS_5xS^5 superstring as Yang-Baxter
sigma models with classical r-matrices satisfying the classical Yang-Baxter
equation (CYBE). An essential point is that the classical r-matrices are
composed of Cartan generators only and then generate abelian twists. We present
examples of the r-matrices that lead to real \gamma-deformations of the
AdS_5xS^5 superstring. Finally we discuss a possible classification of
integrable deformations and the corresponding gravity solution in terms of
solutions of CYBE. This classification may be called the gravity/CYBE
correspondence.Comment: 18 pages, no figure, LaTeX, v2:references and further clarifications
adde
On the classical equivalence of monodromy matrices in squashed sigma model
We proceed to study the hybrid integrable structure in two-dimensional
non-linear sigma models with target space three-dimensional squashed spheres. A
quantum affine algebra and a pair of Yangian algebras are realized in the sigma
models and, according to them, there are two descriptions to describe the
classical dynamics 1) the trigonometric description and 2) the rational
description, respectively. For every description, a Lax pair is constructed and
the associated monodromy matrix is also constructed. In this paper we show the
gauge-equivalence of the monodromy matrices in the trigonometric and rational
description under a certain relation between spectral parameters and the
rescalings of sl(2) generators.Comment: 32pages, 3figures, references added, introduction and discussion
sections revise
The classical origin of quantum affine algebra in squashed sigma models
We consider a quantum affine algebra realized in two-dimensional non-linear
sigma models with target space three-dimensional squashed sphere. Its affine
generators are explicitly constructed and the Poisson brackets are computed.
The defining relations of quantum affine algebra in the sense of the Drinfeld
first realization are satisfied at classical level. The relation to the
Drinfeld second realization is also discussed including higher conserved
charges. Finally we comment on a semiclassical limit of quantum affine algebra
at quantum level.Comment: 25 pages, 2 figure
The Wave Speed of Intergradation Zone in Two-Species Lattice Muellerian Mimicy Model
A spatially explicit model is studied to analyse the movement of coupled clines in two-species Muuellerian mimicry system as exemplified by the comimicking helicoiine butterflies in Central-South America "Heliconius erato" and "Heliconius melpomene". In this system, a pair of comimicking wing patterns of two species (mimicry ring) is found in a geographical region but another pair of wing patterns is found in a different geographical region. The distribution of mimicry rings thus forms a spatial mosaic in a large geographical scale, and the mechanism responsible for their stable maintenance has been a long-standing question in evolutionary biology. We here examine the speed of the movement of boundaries that divide the regions inhabited by different mimetic morphs in each comimicking species, by assuming coupled two-state stochastic cellular automatons where the flipping rate of the site occupied by a mimetic morph depends on the local density of the same morph and of the comimicking morph in the other species. The speed of cline movement shows a complex dependence on the coupling parameter between mimetic species -greater coupling of comimicking morphs between species slows down the cline movement only when the reduction in predation rate exhibits diminishing return to the increase of local mimetic morph density. The analytical predictions are confirmed by the results of Monte Carlo simulations. The speed of advance is quite different from that predicted from the conventional reaction-diffusion model, indicating that demographic stochasticity plays a critical role in determining the speed of cline movement. We also examine if the spatial heterogeneity in migration rate can stably maintain clines
Hybrid classical integrable structure of squashed sigma models -- a short summary
We give a short summary of our recent works on the classical integrable
structure of two-dimensional non-linear sigma models defined on squashed
three-dimensional spheres. There are two descriptions to describe the classical
dynamics, 1) the rational description and 2) the trigonometric description. It
is possible to construct two different types of Lax pairs depending on the
descriptions, and the classical integrability is shown by computing classical
r/s-matrices satisfying the extended Yang-Baxter equation in both descriptions.
In the former the system is described as an integrable system of rational type.
On the other hand, in the latter it is described as trigonometric type. There
exists a non-local map between the two descriptions and those are equivalent.
This is a non-local generalization of the left-right duality in principal
chiral models.Comment: 10 pages, Proceedings of QTS7, Prague, Czech Republic, 201
On classical q-deformations of integrable sigma-models
JHEP is an open-access journal funded by SCOAP3 and licensed under CC BY 4.0A procedure is developed for constructing deformations of integrable σ-models which are themselves classically integrable. When applied to the principal chiral model on any compact Lie group F, one recovers the Yang-Baxter σ-model introduced a few years ago by C. Klimčík. In the case of the symmetric space σ-model on F/G we obtain a new one-parameter family of integrable σ-models. The actions of these models correspond to a deformation of the target space geometry and include a torsion term. An interesting feature of the construction is the q-deformation of the symmetry corresponding to left multiplication in the original models, which becomes replaced by a classical q-deformed Poisson-Hopf algebra. Another noteworthy aspect of the deformation in the coset σ-model case is that it interpolates between a compact and a non-compact symmetric space. This is exemplified in the case of the SU(2)/U(1) coset σ-model which interpolates all the way to the SU(1, 1)/U(1) coset σ-modelPeer reviewedFinal Published versio
Classical integrability of Schrodinger sigma models and q-deformed Poincare symmetry
We discuss classical integrable structure of two-dimensional sigma models
which have three-dimensional Schrodinger spacetimes as target spaces. The
Schrodinger spacetimes are regarded as null-like deformations of AdS_3. The
original AdS_3 isometry SL(2,R)_L x SL(2,R)_R is broken to SL(2,R)_L x U(1)_R
due to the deformation. According to this symmetry, there are two descriptions
to describe the classical dynamics of the system, 1) the SL(2,R)_L description
and 2) the enhanced U(1)_R description. In the former 1), we show that the
Yangian symmetry is realized by improving the SL(2,R)_L Noether current. Then a
Lax pair is constructed with the improved current and the classical
integrability is shown by deriving the r/s-matrix algebra. In the latter 2), we
find a non-local current by using a scaling limit of warped AdS_3 and that it
enhances U(1)_R to a q-deformed Poincare algebra. Then another Lax pair is
presented and the corresponding r/s-matrices are also computed. The two
descriptions are equivalent via a non-local map.Comment: 20 pages, no figure, further clarification and references adde
Topological classification of vortex-core structures of spin-1 Bose-Einstein condensates
We classify vortex-core structures according to the topology of the order
parameter space. By developing a method to characterize how the order parameter
changes inside the vortex core. We apply this method to the spin-1
Bose-Einstein condensates and show that the vortex-core structures are
classified by winding numbers that are locally defined in the core region. We
also show that a vortex-core structure with a nontrivial winding number can be
stabilized under a negative quadratic Zeeman effect.Comment: 16 pages, 6 figure
Bistability patterns and nonlinear switching with very high contrast ratio in a 1550 nm quantum dash semiconductor laser
We report on the experimental observation of optical bistability (OB) and nonlinear switching (NS) in a nanostructure laser; specifically a 1550 nm quantum dash Fabry-Perot laser subject to external optical injection and operated in reflection. Different shapes of optical bistability and nonlinear switching, anticlockwise and clockwise, with very high on-off contrast ratio (up to 180:1) between output states were experimentally measured. These results added to the potential of nanostructure lasers for enhanced performance offer promise for use in fast all-optical signal processing applications in optical networks. © 2012 American Institute of Physics
VSOP observation of the quasar PKS 2215+020: a new laboratory for core-jet physics at z=3.572
We report results of a VSOP (VLBI Space Observatory Programme) observation of
a high redshift quasar PKS 2215+020 (z=3.572). The ~1 milliarcsecond resolution
image of the quasar reveals a prominent `core-jet' structure on linear scales
from 5/h to 300/h pc ($H_0=100*h km/(s*Mpc). The brightness temperatures and
sizes of bright features identified in the jet are consistent with emission
from relativistic shocks dominated by adiabatic energy losses. The jet is
powered by the central black hole with estimated mass of ~4*10^9 solar masses.
Comparisons with VLA and ROSAT observations indicate a possible presence of an
extended radio/X-ray halo surrounding 2215+020.Comment: 15 pages, 6 figures, aastex macros; accepted for publication in The
Astrophysical Journal, V.546, N.2 *(January 10 2001
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