On the equations of motion of point-particle binaries at the third post-Newtonian order

We investigate the dynamics of two point-like particles through the third post-Newtonian (3PN) approximation of general relativity. The infinite self-field of each point-mass is regularized by means of Hadamard's concept of "partie finie". Distributional forms associated with the regularization are used systematically in the computation. We determine the stress-energy tensor of point-like particles compatible with the previous regularization. The Einstein field equations in harmonic coordinates are iterated to the 3PN order. The 3PN equations of motion are Lorentz-invariant and admit a conserved energy (neglecting the 2.5PN radiation reaction). They depend on an undetermined coefficient, in agreement with an earlier result of Jaranowski and Schafer. This suggests an incompleteness of the formalism tin this stage of development) at the 3PN order. In this Letter we present the equations of motion in the center-of-mass frame and in the case of circular orbits. (C) 2000 Elsevier Science B.V. All rights reserved.