Radiation reaction at 3.5 post-Newtonian order in effective field theory
Chad R. Galley, Adam K. Leibovich
TL;DR
The paper derives radiation-reaction forces through $3.5$PN for compact binary inspirals using an effective field theory framework augmented by a rigorous dissipative variational principle. It computes contributions from mass quadrupole, mass octupole, and current quadrupole via Feynman diagrams and confirms agreement with the established Iyer–Will results, providing a non-trivial validation of the extended variational method. The work, together with prior EFT results, nearly completes the spinning-binary equations of motion at $3.5$PN, leaving only the spin–orbit piece of the $3.5$PN potential. This approach also sets the stage for future higher-order radiation-reaction calculations and tail-term corrections at $4$PN and beyond.
Abstract
We derive the radiation reaction forces on a compact binary inspiral through 3.5 order in the post-Newtonian expansion using the effective field theory approach. We utilize a recent formulation of Hamilton's variational principle that rigorously extends the usual Lagrangian and Hamiltonian formalisms to dissipative systems, including the inspiral of a compact binary from the emission of gravitational waves. We find agreement with previous results, which thus provides a non-trivial confirmation of the extended variational principle. The results from this work nearly complete the equations of motion for the generic inspiral of a compact binary with spinning constituents through 3.5 post-Newtonian order, as derived entirely with effective field theory, with only the spin-orbit corrections to the potential at 3.5 post-Newtonian remaining.
