Conservative Dynamics of Binary Systems to Third Post-Minkowskian Order from the Effective Field Theory Approach

We derive the conservative dynamics of nonspinning binaries to third post-Minkowskian order, using the effective field theory (EFT) approach introduced in [G. KIM and R. A. Porto, J. High Energy Phys. 11 (2020) 106] together with the boundary-to-bound dictionary developed in [G. Kalin and R. A. Porto, J. High Energy Phys. 01 (2020) 072; J. High Energy Phys. 02 (2020) 120.]. The main ingredient is the scattering angle, which we compute to O(G(3)) via Feynman diagrams. Adapting to the EFT framework powerful tools from the amplitudes program, we show how the associated (master) integrals are bootstrapped to all orders in velocities via differential equations. Remarkably, the boundary conditions can be reduced to the same integrals that appear in the EFT with post-Newtonian sources. For the sake of comparison, we reconstruct the Hamiltonian and the classical limit of the scattering amplitude. Our results are in perfect agreement with those in Bern et al. [Phys. Rev. Lett. 122, 201603 (2019); J. High Energy Phys. 10 (2019) 206].