The N=8 Supergravity Hamiltonian as a Quadratic Form
  We conjecture that the light-cone Hamiltonian of N=8 Supergravity can be expressed as a quadratic form. We explain why this rewriting is unique to maximally supersymmetric theories. The N=8 quartic interaction vertex is constructed and used to verify that this conjecture holds to second order in the coupling constant. 
Sudarshan Ananth, Lars Brink, Rainer Heise, Harald G. Svendsen