The Dynamics of D-3-brane Dyons and Toric Hyper-K\"ahler manifolds

We find the dyonic worldvolume solitons due to parallel (p,q) strings ending on a D-3-brane. These solutions preserve 1/4 of bulk supersymmetry. Then we investigate the scattering of well-separated dyons and find that their moduli space is a toric hyper-K\"ahler manifold. In addition, we present the worldvolume solitons of the D-3-brane which are related by duality to the M-theory configuration of two orthogonal membranes ending on a M-5-brane. We show that these solitons preserve 1/8 of supersymmetry and compute their effective action.