The ${\cal N}=4$ Supergravity NMHV six-point one-loop amplitude
  We construct the six-point NMHV one-loop amplitude in ${\cal N}=4$ supergravity using unitarity and recursion. The use of recursion requires the introduction of rational descendants of the cut-constructible pieces of the amplitude and the computation of the non-standard factorisation terms arising from the loop integrals. 
David C. Dunbar and Warren B. Perkins
hep-th