All Tree-Level MHV Form Factors in $\mathcal{N}=4$ SYM from Twistor   Space
  We incorporate all gauge-invariant local composite operators into the twistor-space formulation of N=4 SYM theory, detailing and expanding on ideas we presented recently in arXiv:1603.04471. The vertices for these operators contain infinitely many terms and we show how they can be constructed by taking suitable derivatives of a light-like Wilson loop in twistor space and shrinking it down to a point. In particular, these vertices directly yield the tree-level MHV super form factors of all composite operators in N=4 SYM theory. 
Laura Koster, Vladimir Mitev, Matthias Staudacher, Matthias Wilhelm
hep-th math-ph math.MP