Recursion relations for the multiparton collinear limit and splitting   functions
  We present a systematic method to evaluate the splitting functions for tree-level QCD processes where m partons approach the collinear limit. The splitting functions are computed by deriving on-shell recursion equations, which are similar to the Berends-Giele recursion relations for off-shell currents. 
Stefano Catani, Petros Draggiotis, Germ\'an Rodrigo
hep-ph hep-th