Article

# Dynamical structure factor at small q for the XXZ spin-1/2 chain

• ##### S. R. White
Journal of Statistical Mechanics Theory and Experiment (Impact Factor: 1.87). 06/2007; DOI: 10.1088/1742-5468/2007/08/P08022
Source: arXiv

ABSTRACT We combine Bethe Ansatz and field theory methods to study the longitudinal dynamical structure factor S^{zz}(q,omega) for the anisotropic spin-1/2 chain in the gapless regime. Using bosonization, we derive a low energy effective model, including the leading irrelevant operators (band curvature terms) which account for boson decay processes. The coupling constants of the effective model for finite anisotropy and finite magnetic field are determined exactly by comparison with corrections to thermodynamic quantities calculated by Bethe Ansatz. We show that a good approximation for the shape of the on-shell peak of S^{zz}(q,omega) in the interacting case is obtained by rescaling the result for free fermions by certain coefficients extracted from the effective Hamiltonian. In particular, the width of the on-shell peak is argued to scale like delta omega_{q} ~ q^2 and this prediction is shown to agree with the width of the two-particle continuum at finite fields calculated from the Bethe Ansatz equations. An exception to the q^2 scaling is found at finite field and large anisotropy parameter (near the isotropic point). We also present the calculation of the high-frequency tail of S^{zz}(q,\omega) in the region delta omega_{q}<< omega-vq << J using finite-order perturbation theory in the band curvature terms. Both the width of the on-shell peak and the high-frequency tail are compared with S^{zz}(q,omega) calculated by Bethe Ansatz for finite chains using determinant expressions for the form factors and excellent agreement is obtained. Finally, the accuracy of the form factors is checked against the exact first moment sum rule and the static structure factor calculated by Density Matrix Renormalization Group (DMRG). Comment: 67 pages, 25 figures

0 Bookmarks
·
78 Views
• Source
##### Article: Form factors in SU(3)-invariant integrable models
[Hide abstract]
ABSTRACT: We study SU(3)-invariant integrable models solvable by nested algebraic Bethe ansatz. We obtain determinant representations for form factors of diagonal entries of the monodromy matrix. This representation can be used for the calculation of form factors and correlation functions of the XXX SU(3)-invariant Heisenberg chain.
Journal of Statistical Mechanics Theory and Experiment 11/2012; 2013(04). · 1.87 Impact Factor
• Source
##### Article: Scalar products in models with $GL(3)$ trigonometric $R$-matrix. General case
[Hide abstract]
ABSTRACT: We study quantum integrable models with $GL(3)$ trigonometric $R$-matrix solvable by the nested algebraic Bethe ansatz. We analyze scalar products of generic Bethe vectors and obtain an explicit representation for them in terms of a sum with respect to partitions of Bethe parameters. This representation generalizes known formula for the scalar products in the models with $GL(3)$-invariant $R$-matrix.
01/2014;
• Source
##### Article: Scalar products in models with GL(3) trigonometric R-matrix. Highest coefficient
[Hide abstract]
ABSTRACT: We study quantum integrable models with GL(3) trigonometric R-matrix solvable by the nested algebraic Bethe ansatz. Scalar products of Bethe vectors in such models can be expressed in terms of a bilinear combination of the highest coefficients. We show that in the models with GL(3) trigonometric R-matrix there exist two different highest coefficients. We obtain various representations for them in terms of sums over partitions. We also prove several important properties of the highest coefficients, which are necessary for the evaluation of the scalar products.
11/2013; 178(3).