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arXiv:cond-mat/9604143 · Physical Review Letters

Exact Solution and Spectral Flow for Twisted Haldane-Shastry Model

Takahiro Fukui, Norio Kawakami

Published May 27, 1996• 19 citations
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Abstract

The exact solution of the spin chain model with $1/{r}^{2}$ exchange is found for twisted boundary conditions. The spectrum thus obtained can be reproduced by the asymptotic Bethe ansatz. The spectral flow of each eigenstate is determined exactly as a function of the twist angle. We find that the period $4\ensuremath{\pi}$ for the ground state nicely fits in with the notion of fractional exclusion statistics.

DOI
10.1103/physrevlett.76.4242

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In this paper, we consider the parameterization of the spectra of the three-state critical Potts quantum chain with integrable twisted boundary conditions in terms of Bethe ansatz type equations. The Bethe equations are found by investigating the structure of the eigenvalues of the respective twisted transfer matrices, and with the help of certain identities satisfied by the product of transfer matrices operators. We have studied the completeness of the spectrum in terms of the Bethe roots for small lattice sizes and have computed the eigenstate momenta. We found that the spins of the low-lying excitations can have fractional values in accordance with predictions of the underlying conformal field theory. We argue that our framework can be used to build integrable Hamiltonians whose spectra are determined by mixing different toroidal boundary conditions.
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Exact solution of the quantum integrable model associated with the twisted D3(2) {\mathrm{D}}_3^{(2)} D3(2)​ algebra
Abstract We generalize the nested off-diagonal Bethe ansatz method to study the quantum chain associated with the twisted D3(2) {D}_3^{(2)} D3(2)​ D 3 2 algebra (or the D3(2) {D}_3^{(2)} D3(2)​ D 3 2 model) with either periodic or integrable open boundary conditions. We obtain the intrinsic operator product identities among the fused transfer matrices and find a way to close the recursive fusion relations, which makes it possible to determinate eigenvalues of transfer matrices with an arbitrary anisotropic parameter η. Based on them, and the asymptotic behaviors and values at certain points, we construct eigenvalues of transfer matrices in terms of homogeneous T − Q relations for the periodic case and inhomogeneous ones for the open case with some off-diagonal boundary reflections. The associated Bethe ansatz equations are also given. The method and results in this paper can be generalized to the Dn+1(2) {D}_{n+1}^{(2)} Dn+1(2)​ D n + 1 2 model and other high rank integrable models.