Recursive equations for arbitrary scattering processes
  The usefulness of recursive equations to compute scattering matrix elements for arbitrary processes is discussed. Explicit results at tree and one-loop order, obtained by the HELAC/PHEGAS package that is based on the Dyson-Schwinger recursive equations approach, are briefly presented. 
P.Draggiotis, A.van Hameren, R.Kleiss, A.Lazopoulos, C.G.Papadopoulos,   M.Worek