Numerical Unitarity for Binary Dynamics

Abstract: We present a calculation of the conservative two-body Hamiltonian of a compact binary system including a spinning black hole. We include up-to third order corrections in Newton's constant $G$, all orders in velocity, and linear and quadratic terms in spin. The results are obtained from the classical limit of two-loop scattering amplitudes involving two massive scalars and two massive spin-1 particles minimally coupled to gravity. We discuss the usage of numerical techniques in our computation. In particular we show how the numerical unitarity method is well suited to obtain results of relevance to the physics program of current and future gravitational wave observatories.