Progress on Ultraviolet Finiteness of Supergravity

Understand

In this lecture we summarize recent calculations pointing to the possible ultraviolet finiteness of N = 8 supergravity in four dimensions.

• We outline the modern unitarity method, which enables multiloop calculations in this theory and allows us to exploit a remarkable relation between tree-level gravity and gauge-theory amplitudes.
• We also describe a link between observed cancellations at loop level and improved behavior of tree-level amplitudes under large complex deformations of momenta.