Multi-Particle Processes in the Standard Model without Feynman Diagrams
  A method to efficiently compute, in a automatic way, helicity amplitudes for arbitrary scattering processes at leading order in the Standard Model is presented. The scattering amplitude is evaluated recursively through a set of Dyson-Schwinger equations. The computational cost of this algorithm grows asymptotically as 3^n, where n is the number of particles involved in the process, compared to n! in the traditional Feynman graphs approach. Unitary gauge is used and mass effects are available as well. Additionally, the color and helicity structures are appropriately transformed so the usual summation is replaced by Monte Carlo techniques. Some results related to the production of vector bosons and the Higgs boson in association with jets are also presented. 
Costas G. Papadopoulos and Malgorzata Worek