Department of Physics,
Ochanomizu University,
Ohtsuka 2-1-1, Bunkyo-ku,
Tokyo 112-8610,
E-mail: deguchi@phys.ocha.ac.jp

The sl(2) loop algebra symmetry of the XXZ spin chain: the Drinfeld polynomials of regular XXZ Bethe states

We show  that regular Bethe ansatz eigenvectors of the XXZ spin chain at roots of unity are highest weight vectors and generate irreducible representations of the $sl(2)$ loop algebra. Here the parameter $q$, which is related to the XXZ anisotropy $\Delta$ through $\Delta=(q+1/q)/2$, is given by a root of unity, $q$ to the $2N$th power equals to 1, for an integer $N$.

See cond-mat/0503564.