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Anjan Kundu

Publications and source records attributed to Anjan Kundu.

66 records · Page 4Linked to original sources
arXiv1997

Unifying structures in quantum integrable systems

Basic concepts of quantum integrable systems (QIS) are presented stressing on the unifying structures underlying such diverse models. Variety of ultralocal and nonultralocal models is shown to be described by a few basic relations defining novel algebraic entries. Such properties can generate and classify integrable models systematically and also help to solve exactly their eigenvalue problem in an almost model-independent way. The unifying thread stretches also beyond the QIS to establish its deep connections with statistical models, conformal field theory etc. as well as with abstract mathematical objects like quantum group, braided or quadratic algebra

solv-int↗
arXiv1997

Quantum Integrable Systems: Basic Concepts and Brief Overview

An overview of the quantum integrable systems (QIS) is presented. Basic concepts of the theory are highlighted stressing on the unifying algebraic properties, which not only helps to generate systematically the representative Lax operators of different models, but also solves the related eigenvalue problem in an almost model independent way. Difference between the approaches in the integrable ultralocal and nonultralocal quantum models are explained and the interrelation between the QIS and other subjects are focussed on.

hep-th↗
arXiv1997

Multi-parameter deformed and nonstandard $Y(gl_M)$ Yangian symmetry in a novel class of spin Calogero-Sutherland models

It is well known through a recent work of Bernard, Gaudin, Haldane and Pasquier (BGHP) that the usual spin Calogero-Sutherland (CS) model, containing particles with $M$ internal degrees of freedom, respects the $Y(gl_M)$ Yangian symmetry. By following and suitably modifying the approach of BGHP, in this article we construct a novel class of spin CS models which exhibit multi-parameter deformed or `nonstandard' variants of $Y(gl_M)$ Yangian symmetry. An interesting feature of such CS Hamiltonians is that they contain many-body spin dependent interactions, which can be calculated directly from the associated rational solutions of Yang-Baxter equation. Moreover, these spin dependent interactions often lead to `anyon like' representations of permutation algebra on the combined internal space of all particles. We also find out the general forms of conserved quantities as well as Lax pairs for the above mentioned class of spin CS models, and describe the method of constructing their exact wave functions.

hep-th↗
arXiv1996

Quantum Integrable Systems: Construction, Solution, Algebraic Aspect

Various aspects of the theory of quantum integrable systems are reviewed. Basic ideas behind the construction of integrable ultralocal and nonultralocal quantum models are explored by exploiting the underlying algebraic structures related to the Yang-Baxter equations. Physical meaning of abstract mathematical notions like universal R-matrix, quantized algebras, Sklyanin algebra, braided algebra, Hopf algebra etc. and the role played by them in integrable systems are highlighted. Systematic construction of quantum integrable lattice as well as field models and their exact excitation spectra are presented through examples. The coordinate and algebraic formulations of the Bethe ansatz are illustrated with comparison, along with the description of nested and functional Bethe ansatzes. The techniques for deriving quantum Hamiltonians from the Lax operators are demonstrated on concrete models. The exposition of this review is kept in a fairly elementary level with emphasis on the physical contents.

hep-th↗
arXiv1996

Generation of Integrable Quantum Nonultralocal Model through Braided Yang-Baxter Equation

Formulating quantum integrability for nonultralocal models (NM) parallel to the familiar approach of inverse scattering method is a long standing problem. After reviewing our result regarding algebraic structures of ultralocal models, we look for the algebra underlying NM. We propose an universal equation represented by braided Yang-Baxter equation and able to derive all basic equations of the known models like WZWN model, nonabelian Toda chain, quantum mapping etc. As further useful application we discover new integrable quantum NM, e.g. mKdV model, anyonic model, Kundu-Eckhaus equation and derive SUSY models and reflection equation from the nonultralocal view point.

hep-th↗
arXiv1995

Exact Bethe ansatz solution of nonultralocal quantum mKdV model

A lattice regularized Lax operator for the nonultralocal modified Korteweg de Vries (mKdV) equation is proposed at the quantum level with the basic operators satisfying a $q$-deformed braided algebra. Finding further the associated quantum $R$ and $Z$-matrices the exact integrability of the model is proved through the braided quantum Yang--Baxter equation, a suitably generalized equation for the nonultralocal models. Using the algebraic Bethe ansatz the eigenvalue problem of the quantum mKdV model is exactly solved and its connection with the spin-$\ha$ XXZ chain is established, facilitating the investigation of the corresponding conformal properties.

hep-th↗
arXiv1994

Generation of a quantum integrable class of discrete-time or relativistic periodic Toda chains

A new integrable class of quantum models representing a family of different discrete-time or relativistic generalisations of the periodic Toda chain (TC), including that of a recently proposed classical close to TC model [7] is presented. All such models are shown to be obtainable from a single ancestor model at different realisations of the underlying quantised algebra. As a consequence the $(2\times 2)$ Lax operators and the associated quantum $R$-matrices for these models are easily derived ensuring their quantum integrability. It is shown that the functional Bethe ansatz developed for the quntum TC is trivially generalised to achieve seperation of variables also for the present models.

hep-th↗
arXiv1994

Classical integrable lattice models through quantum group related formalism

We translate effectively our earlier quantum constructions to the classical language and using Yang-Baxterisation of the Faddeev-Reshetikhin-Takhtajan algebra are able to construct Lax operators and associated $r$-matrices of classical integrable models. Thus new as well as known lattice systems of different classes are generated including new types of collective integrable models and canonical models with nonstandard $r$ matrices.

hep-th↗
arXiv1993

New integrable hierarchies gauge generated from constrained KP

Exploiting the residual gauge freedom in the formulation of constrained KP hierarchy a number of new integrable systems are derived including hierarchies of Kundu-Eckhaus equation and higher order nonlinear extensions of Yajima-Oikawa and Melnikov hierarchy. In the multicomponent case such gauge freedom generates novel multicomponent as well as vector generalisations of the above systems, while the constrained modified KP hierarchy is found to yield another set of equations like derivative NLS, Gerdjikov-Ivanov equation and chen-Lee-Liu equation depending on the gauge choice.

hep-th↗
arXiv1993

Derivative and higher order extensions of Davey-Stewartson equation from matrix KP hierarchy

It is shown that the matrix KP hierarchy can yield new integrable equations in $(2+1)$-dimensions along with the corresponding Lax pair. For particular gauge choice this may result derivative and also a higher order nonlinear extension of the Devay-Stewartson equation (DSE),the higher order DSE being a higher dimensional generalisation of the Kundu- Eckhaus equation. Such gauge transformation is shown also to produce significant extensions to the constrained matrix KP system.

hep-th↗
arXiv1993

Universality of the universal R-matrix and applications to quantum integrable systems

Results obtained by us are overviewed from a general set up. The universal $R$-matrix is exploited to obtain various important relations and structures involved in quantum group algebra, which are used subsequently for generating different classes of quantum integrable systems through a systematic scheme. This recovers known models as well as discovers a series of new ones.

hep-th↗