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arXiv:solv-int/9810007

Quelques applications de l'Ansatz de Bethe (Some applications of the Bethe Ansatz)

Paul Zinn-Justin

Published Oct 11, 1998• 3 citations
arXivHTMLPDF

Abstract

The Bethe Ansatz is a method that is used in quantum integrable models in order to solve them explicitly. This method is explained here in a general framework, which applies to 1D quantum spin chains, 2D statistical lattice models (vertex models) and relativistic field theories with 1 space dimension and 1 time dimension. The connection with quantum groups is expounded. Several applications are then presented. Finite size corrections are calculated via two methods: The Non-Linear Integral Equations, which are applied to the study of the states of the affine Toda model with imaginary coupling, and their interpolation between the high energy (ultra-violet) and low energy (infra-red) regions; and the Thermodynamic Bethe Ansatz Equations, along with the associated Fusion Equations, which are used to determine the thermodynamic properties of the generalized multi-channel Kondo model. The latter is then studied in more detail, still using the Bethe Ansatz and quantum groups, so as to characterize the spectrum of the low energy excitations.

DOI
10.48550/arxiv.solv-int/9810007

Related papers

Quelques applications de l'ansatz de bethe

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L'ansatz de bethe est une technique utilisee dans les modeles quantiques integrables pour une resolution explicite de ceux-ci. Cette technique est exposee ici dans un cadre general, valable pour les chaines de spin quantiques 1d, les modeles statistiques sur reseau (du type modeles de vertex) 2d et les theories des champs relativistes a 1 dimension d'espace et 1 dimension de temps. Le lien avec les groupes quantiques est explicite. Plusieurs applications sont alors presentees. Le calcul des corrections de taille finie est effectuee par deux methodes : les equations non-lineaires integrales, que l'on applique a l'etude des etats du modele de toda affine en constante de couplage imaginaire sur un espace compactifie, et leur interpolation entre la region de haute energie (ultra-violette) et de basse energie (infra-rouge) ; et les equations d'ansatz de bethe thermodynamique, ainsi que les equations de fusion qui leur sont associees, dont on se sert pour determiner la thermodynamique du modele de kondo multi-canal generalise. Ce dernier est ensuite etudie plus en detail, toujours par l'ansatz de bethe et les groupes quantiques, de facon a caracteriser le spectre des excitations de basse energie.

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Bethe Ansatz

Gleb Eduardovich Arutyunov

The Bethe Ansatz is a powerful method in the theory of quantum integrable models, essential for determining the energy spectrum of dynamical systems - from spin chains in magnetism to models in high-energy physics. This book provides a comprehensive introduction to the Bethe ansatz, from its historical roots to modern developments. First introduced by Hans Bethe in 1931, the method has evolved into a universal framework encompassing algebraic, analytic, thermodynamic, and functional forms. The book explores various Bethe ansatz techniques and their interrelations, covering both coordinate and algebraic versions, with particular attention to nested structures and functional relations involving transfer matrices. Advanced tools such as the separation of variables method are presented in detail. With a wealth of worked examples and precise calculations, this volume serves as an accessible and rigorous reference for graduate students and researchers in mathematical physics and integrable systems.

Cambridge University Press eBooks•Apr 27, 2026•1 citation
The Bethe Ansatz is a method that is used in quantum integrable models in order to solve them explicitly. This method is explained here in a general framework, which applies to 1D quantum spin chains, 2D statistical lattice models (vertex models) and relativistic field theories with 1 space dimension and 1 time dimension. The connection with quantum groups is expounded. Several applications are then presented. Finite size corrections are calculated via two methods: The Non-Linear Integral Equations, which are applied to the study of the states of the affine Toda model with imaginary coupling, and their interpolation between the high energy (ultra-violet) and low energy (infra-red) regions; and the Thermodynamic Bethe Ansatz Equations, along with the associated Fusion Equations, which are used to determine the thermodynamic properties of the generalized multi-channel Kondo model. The latter is then studied in more detail, still using the Bethe Ansatz and quantum groups, so as to characterize the spectrum of the low energy excitations.
L'ansatz de bethe est une technique utilisee dans les modeles quantiques integrables pour une resolution explicite de ceux-ci. Cette technique est exposee ici dans un cadre general, valable pour les chaines de spin quantiques 1d, les modeles statistiques sur reseau (du type modeles de vertex) 2d et les theories des champs relativistes a 1 dimension d'espace et 1 dimension de temps. Le lien avec les groupes quantiques est explicite. Plusieurs applications sont alors presentees. Le calcul des corrections de taille finie est effectuee par deux methodes : les equations non-lineaires integrales, que l'on applique a l'etude des etats du modele de toda affine en constante de couplage imaginaire sur un espace compactifie, et leur interpolation entre la region de haute energie (ultra-violette) et de basse energie (infra-rouge) ; et les equations d'ansatz de bethe thermodynamique, ainsi que les equations de fusion qui leur sont associees, dont on se sert pour determiner la thermodynamique du modele de kondo multi-canal generalise. Ce dernier est ensuite etudie plus en detail, toujours par l'ansatz de bethe et les groupes quantiques, de facon a caracteriser le spectre des excitations de basse energie.
Abstract We give a pedagogical introduction to the Bethe ansatz techniques in integrable QFTs and spin chains. We first discuss and motivate the general framework of asymptotic Bethe ansatz for the spectrum of integrable QFTs in large volume, based on the exact S -matrix. Then we illustrate this method in several concrete theories. The first case we study is the SU (2) chiral Gross–Neveu model. We derive the Bethe equations via algebraic Bethe ansatz, solving in the process the Heisenberg XXX spin chain. We discuss this famous spin chain model in some detail, covering in particular the coordinate Bethe ansatz, some properties of Bethe states, and the classical scaling limit leading to finite-gap equations. Then we proceed to the more involved SU (3) chiral Gross–Neveu model and derive the Bethe equations using nested algebraic Bethe ansatz to solve the arising SU (3) spin chain. Finally we show how a method similar to the Bethe ansatz works in a completely different setting, namely for the 1D oscillator in quantum mechanics.
Abstract The Thermodynamic Bethe Ansatz (TBA) allows us to study finite size and finite temperature effects of an integrable model. This chapter investigates the integral equations that determine the free energy and gives their physical interpretation. It discusses Casimir energy, Bethe relativistic wave function, the derivation of thermodynamics, the meaning of pseudo-energy (dressed energy and momentum), infrared and ultraviolet limits, the coefficient of bulk energy, the general form of the TBA equations, the thermodynamics of the free field theories, L-channel quantization and the LeClair–Mussardo formula. It also covers the application of the Yang–Lee S-matrix, the magnetic field Ising model, and the tricritical Ising model.
Abstract The thermodynamics of a quantum field theory in an infinite volume can be determined by its S-matrix. This idea, originally proposed by R. Dashen, S.K. Ma, and H.J. Berstein, has been widely used to study the thermal properties of the integrable field theories in (1 + 1) dimensions. The reason consists of the particularly simple properties of these scattering matrices, as discussed in the previous two chapters, and the possibility to generalize to the relativistic case the thermodynamics Bethe ansatz (TBA) techniques successfully applied to non-relativistic problems by C.N. Yang and C.P. Yang. In the TBA approach, the derivation of the thermodynamics of a purely elastic scattering theory reduces to finding the solution of a set of nonlinear integral equations that rule the energies of the particle excitations and their statistical distribution.
In this article we review recent developments in the one-dimensional Bethe ansatz solvable multi-chain quantum models. The algebraic version of the Bethe ansatz (the quantum inverse scattering method) permits us to construct new families of integrable Hamiltonians using simple generalizations of the well known constructions of the single-chain model. First we consider the easiest example (`basic' model) of this class of models: the antiferromagnetic two-chain spin-1/2 model with the nearest-neighbour and next-nearest-neighbour spin-frustrating interactions (zigzag chain). We show how the algebra of the quantum inverse scattering method works for this model, and what are the important features of the Hamiltonian (which reveal the topological properties of two dimensions together with the one-dimensional properties). We consider the solution of the Bethe ansatz for the ground state (in particular, commensurate-incommensurate quantum phase transitions present due to competing spin-frustrating interactions are discussed) and construct the thermal Bethe ansatz (in the form of the `quantum transfer matrix') for this model. Then possible generalizations of the basic model are considered: an inclusion of a magnetic anisotropy, higher-spin representations (including the important case of a quantum ferrimagnet), the multi-chain case, internal degrees of freedom of particles at each site, etc. We observe the similarities and differences between this class of models and related exactly solvable models: other groups of multi-chain lattice models, quantum field theory models and magnetic impurity (Kondo-like) models. Finally, the behaviour of non-integrable (less constrained) multi-chain quantum models is discussed.
The Bethe Ansatz is a powerful method in the theory of quantum integrable models, essential for determining the energy spectrum of dynamical systems - from spin chains in magnetism to models in high-energy physics. This book provides a comprehensive introduction to the Bethe ansatz, from its historical roots to modern developments. First introduced by Hans Bethe in 1931, the method has evolved into a universal framework encompassing algebraic, analytic, thermodynamic, and functional forms. The book explores various Bethe ansatz techniques and their interrelations, covering both coordinate and algebraic versions, with particular attention to nested structures and functional relations involving transfer matrices. Advanced tools such as the separation of variables method are presented in detail. With a wealth of worked examples and precise calculations, this volume serves as an accessible and rigorous reference for graduate students and researchers in mathematical physics and integrable systems.