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

Abstract:
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.