Three-graviton scattering in M-theory

The leading eikonal S-matrix for three-graviton scattering in d = 11 superg ravity and Matrix theory are shown to precisely agree. The result unifies t he source-probe plus recoil approach of Okawa and Yoneya and relaxes the re striction imposed by those authors that all D-particle impact parameters an d velocities are mutually perpendicular. Furthermore, the unified S-matrix approach facilitates a clean-cut study of M-theoretic R-4 curvature correct ions to the low energy supergravity effective action. In particular, the le ading R-4 correction to the three-graviton S-matrix is computed and compare d to the corresponding next to leading order two-loop U(3) amplitude in Mat rix theory. We find a clear disagreement of the two resulting tensor struct ures. (C) 1999 Elsevier Science B.V. All rights reserved.