QUANTUM AFFINE SYMMETRY IN VERTEX MODELS

We study the higher spin analogs of the six-vertex model on the basis of its symmetry under the quantum affine algebra U(q)(sl2). Using the method developed recently for the XXZ spin chain, we formulate the spa ce of states, transfer matrix, vacuum, creation/annihilation operators of particles, and local operators, purely in the language of represen tation theory. We find that, regardless of the level of the representa tion involved, the particles have spin 1/2, and that the n-particle sp ace has an RSOS type structure rather than a simple tensor product of the one-particle space. This agrees with the picture proposed earlier by Reshetikhin.