Infrared behaviour of the one-loop scattering equations and supergravity integrands

Understand

The recently introduced ambitwistor string led to a striking proposal for one-loop maximal supergravity amplitudes, localised on the solutions of the ambitwistor one-loop scattering equations.

• However, these amplitudes have not yet been explicitly analysed due to the apparent complexity of the equations that determine the localisation.
• In this paper we propose an analytic solution to the four-point one-loop scattering equations in the infrared (IR) regime of the amplitude.
• Using this solution, we compute the ambitwistor integrand and demonstrate that it correctly reproduces the four-graviton integrand, in the IR regime.