The exact S -matrix for an osp(2|2) disordered system Original Research Article

We study a two-dimensional disordered system consisting of Dirac fermions coupled to a scalar potential. This model is closely related to a more general disordered system that has been introduced in conjunction with the integer quantum Hall transition. After disorder averaging, the interaction can be written as a marginal osp(2|2) current–current perturbation. The osp(2|2) current–current model in turn can be viewed as the fully renormalized version of an osp(2|2)(1) Toda-type system (at the marginal point). We build nonlocal charges for the Toda system satisfying the Uq[osp(2|2)(1)] quantum superalgebra. The corresponding quantum group symmetry is used to construct a Toda S -matrix for the vector representation. We argue that in the marginal (or rational) limit, this S -matrix gives the exact (Yangian symmetric) physical S -matrix for the fundamental “solitons” of the osp(2|2) current–current model.