Hidden Yangians in 2D massive current algebras

We define non-local conserved currents in massive current algebras in two dimensions. Our approach is algebraic and non-perturbative. The non-local currents give a quantum field realization of the Yangians. We show how the noncocommutativity of the Yangians is related to the non-locality of the currents. We discuss the implications of the existence of non-local conserved charges on theS-matrices.Laboratoire de la Direction des sciences de la matière du Commissariat à l'énergie atomique