11,873 research outputs found
Integral equations for thermodynamics of the osp(1|2s) integrable spin chain
We propose a system of nonlinear integral equations (NLIE), which gives the
free energy of the osp(1|2s) integrable spin chain at finite temperatures. In
contrast with usual thermodynamic Bethe ansatz equations, our new NLIE contain
only a finite number of unknown functions. On deriving NLIE, we use our
osp(1|2s) version of the T-system and the quantum transfer matrix method. Based
on our NLIE, we also calculate the high temperature expansion of the free
energy and the specific heat.Comment: 13 pages, 1 figure, to appear in Phys. Lett. B 544 (2002) 222-23
Quantum groups, Yang-Baxter maps and quasi-determinants
For any quasi-triangular Hopf algebra, there exists the universal R-matrix,
which satisfies the Yang-Baxter equation. It is known that the adjoint action
of the universal R-matrix on the elements of the tensor square of the algebra
constitutes a quantum Yang-Baxter map, which satisfies the set-theoretic
Yang-Baxter equation. The map has a zero curvature representation among
L-operators defined as images of the universal R-matrix. We find that the zero
curvature representation can be solved by the Gauss decomposition of a product
of L-operators. Thereby obtained a quasi-determinant expression of the quantum
Yang-Baxter map associated with the quantum algebra . Moreover,
the map is identified with products of quasi-Pl\"{u}cker coordinates over a
matrix composed of the L-operators. We also consider the quasi-classical limit,
where the underlying quantum algebra reduces to a Poisson algebra. The
quasi-determinant expression of the quantum Yang-Baxter map reduces to ratios
of determinants, which give a new expression of a classical Yang-Baxter map.Comment: 46 page
Determining equations for higher-order decompositions of exponential operators
The general decomposition theory of exponential operators is briefly
reviewed. A general scheme to construct independent determining equations for
the relevant decomposition parameters is proposed using Lyndon words. Explicit
formulas of the coefficients are derived.Comment: 30 page
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