- Published 2003

The symmetries of the twisted XXZ chain alias the six-vertex model at roots of unity are investigated. It is shown that when the twist parameter is chosen to depend on the total spin an infinite-dimensional non-abelian symmetry algebra can be explicitly constructed for all spin sectors. This symmetry algebra is identified to be the upper or lower Borel subalgebra of the sl2 loop algebra. The proof uses only the intertwining property of the six-vertex monodromy matrix and the familiar relations of the six-vertex Yang-Baxter algebra.

@inproceedings{Korff2003TheTX,
title={The twisted XXZ chain at roots of unity revisited},
author={Christian Korff},
year={2003}
}