Employing a change of basis, the so-called factorizing Drinfel'd twist, we construct polarization-free and completely symmetric creation operators for a face type model equivalent to the Belavin model. A resolution of the nested structure of the Bethe vectors is achieved.
We construct Drinfel'd twists for the rational sl ( n ) XXX model giving rise to a completely symmetric representation of the monodromy matrix. We obtain a polarization-free representation of the pseudoparticle creation operators figuring in the construction of the Bethe vectors within the framework of the quantum inverse scattering method. This representation enables us to resolve the hierarchy of the nested Bethe ansatz for the sl ( n ) invariant rational Heisenberg model. Our results generalize the findings of Maillet and Sanchez de Santos for sl (2) models.