A Note on Twistor Gravity Amplitudes
  In a recent paper, Witten proposed a surprising connection between perturbative gauge theory and a certain topological model in twistor space. In particular, he showed that gluon amplitudes are localized on holomorphic curves. In this note we present some preliminary considerations on the possibility of having a similar localization for gravity amplitudes. 
Simone Giombi, Riccardo Ricci, Daniel Robles-Llana and Diego   Trancanelli