Absence of Three-Loop Four-Point Divergences in N=4 Supergravity
  We compute the coefficient of the potential three-loop divergence in pure N=4 supergravity and show that it vanishes, contrary to expectations from symmetry arguments. The recently uncovered duality between color and kinematics is used to greatly streamline the calculation. We comment on all-loop cancellations hinting at further surprises awaiting discovery at higher loops. 
Zvi Bern, Scott Davies, Tristan Dennen, Yu-tin Huang
hep-th