They consider Yang-Mills theory in the light-cone gauge and identify a non-local change of variables that implies, in a pretty straightforward fashion, the Cachazo-Svrček-Witten (CSW) "disconnected" rules for the Yang-Mills scattering amplitudes. Such an understanding of the problem allows them to conjecture that there should be a natural one-loop correction to the CSW Lagrangian, arising from the Jacobian of their field redefinition, and no higher-loop corrections.
Their method shows that the twistor techniques are not merely mysterious bricks included in the third road of quantum gravity - bricks that only magicians like Penrose can comprehend - but instead, they are components of the standard light-cone gauge and spinorial procedures used to work with the usual degrees of freedom.
They start with the Yang-Mills light-cone gauge which means
- A+ = 0
and express the physical components of the Yang-Mills field
- Ax +- i Ay