The Ultraviolet Behavior of N=8 Supergravity at Four Loops

Understand

We describe the construction of the complete four-loop four-particle amplitude of N=8 supergravity.

• The amplitude is ultraviolet finite, not only in four dimensions, but in five dimensions as well.
• The observed extra cancellations provide additional non-trivial evidence that N=8 supergravity in four dimensions may be ultraviolet finite to all orders of perturbation theory.