Exact S-matrices for bound states of a2(1) affine Toda solitons Original Research Article

Using Hollowoodʹs conjecture for the S-matrix for elementary solitons in complex an(1) affine Toda field theories we examine the interactions of bound states of solitons in a2(1) theory. The elementary solitons can form two different kinds of bound states: scalar bound states (the so-called breathers), and excited solitons, which are bound states with non-zero topological charge. We give explicit expressions of all S-matrix elements involving the scattering of breathers and excited solitons and examine their pole structure in detail. It is shown how the poles can be explained in terms of on-shell diagrams, several of which involve a generalized Coleman-Thun mechanism.