Twistor diagrams for all tree amplitudes in gauge theory: a   helicity-independent formalism
  We give a new formalism for pure gauge-theoretic scattering at tree-amplitude level. We first describe a generalization of the Britto-Cachazo-Feng recursion relation in which a significant restriction is removed. We then use twistor diagrams to express all tree amplitudes in a form independent of helicity. A formal procedure involving anticommuting elements is required. We illustrate the results with specific calculations of interest, up to 8 interacting fields. 
Andrew Hodges