It has been recently discovered in the context of the six vertex or XXZ model in the fundamental representation that new symmetries arise when the anisotropy parameter $(q+q^{-1})/2$ is evaluated at roots of unity $q^{N}=1$ . These new symmetries have been linked to an $U(A^{(1)}_1)$ invariance of the transfer matrix and the corresponding spin-chain Hamiltonian.In this paper these results are generalized for odd primitive roots of unity to all vertex models associated with trigonometric solutions of the Yang-Baxter equation by invoking representation independent methods which only take the algebraic structure of the underlying quantum groups $U_q(\\hat g)$ into account. Here $\\hat g$ is an arbitrary Kac-Moody algebra. Employing the notion of the boost operator it is then found that the Hamiltonian and the transfer matrix of the integrable model are invariant under the action of $U(\\hat{g})$ . For the simplest case $\\hat g=A_1^{(1)}$ the discussion is also extended to even primitive roots of unity.It has been recently discovered in the context of the six vertex or XXZ model in the fundamental representation that new symmetries arise when the anisotropy parameter $(q+q^{-1})/2$ is evaluated at roots of unity $q^{N}=1$. These new symmetries have been linked to an $U(A^{(1)}_1)$ invariance of the transfer matrix and the corresponding spin-chain Hamiltonian.In this paper these results are generalized for odd primitive roots of unity to all vertex models associated with trigonometric solutions of the Yang-Baxter equation by invoking representation independent methods which only take the algebraic structure of the underlying quantum groups $U_q(\\hat g)$ into account. Here $\\hat g$ is an arbitrary Kac-Moody algebra. Employing the notion of the boost operator it is then found that the Hamiltonian and the transfer matrix of the integrable model are invariant under the action of $U(\\hat{g})$. For the simplest case $\\hat g=A_1^{(1)}$ the discussion is also extended to even primitive roots of unity.

Jan 1, 200113 citations

The method of vacuum vectors in the theory of Yang - Baxter equation

I. G. Korepanov

In modern terminology, this is the first published paper where the solutions of Yang - Baxter equation "at roots of unity" were analyzed and shown to be related to algebraic curves of genus >1. They are also known now to be connected with the "chiral Potts model". The paper's abstract as written in 1986 reads: "Vacuum vectors of an L-operator form a holomorphic bundle over the vacuum curve of that operator. These notions, as well as the theory of commutation relations of the 6-vertex model, are used in this work for constructing solutions of the Yang - Baxter equation that do not possess a spectral parameter of traditional type".In modern terminology, this is the first published paper where the solutions of Yang - Baxter equation "at roots of unity" were analyzed and shown to be related to algebraic curves of genus >1. They are also known now to be connected with the "chiral Potts model". The paper's abstract as written in 1986 reads: "Vacuum vectors of an L-operator form a holomorphic bundle over the vacuum curve of that operator. These notions, as well as the theory of commutation relations of the 6-vertex model, are used in this work for constructing solutions of the Yang - Baxter equation that do not possess a spectral parameter of traditional type".

arXiv:nlin/0010024Oct 12, 20005 citations

It has been recently discovered in the context of the six vertex or XXZ model in the fundamental representation that new symmetries arise when the anisotropy parameter

(q+q^{-1})/2

is evaluated at roots of unity

q^{N}=1

. These new symmetries have been linked to an

U(A^{(1)}_1)

invariance of the transfer matrix and the corresponding spin-chain Hamiltonian.In this paper these results are generalized for odd primitive roots of unity to all vertex models associated with trigonometric solutions of the Yang-Baxter equation by invoking representation independent methods which only take the algebraic structure of the underlying quantum groups

U_q(\\hat g)

into account. Here

\\hat g

is an arbitrary Kac-Moody algebra. Employing the notion of the boost operator it is then found that the Hamiltonian and the transfer matrix of the integrable model are invariant under the action of

U(\\hat{g})

. For the simplest case

\\hat g=A_1^{(1)}

the discussion is also extended to even primitive roots of unity.