3-GRAVITON SCATTERING IN MATRIX-THEORY REVISITED

We consider a subset of the terms In the effective potential describin g three-graviton interactions in Matrix theory and in classical eleven -dimensional supergravity. In agreement with the results of Dine and R ajaraman, we find that these terms vanish in Matrix theory. We show th at the absence of these terms is compatible with the classical supergr avity theory when the theory is compactified in a lightlike direction, resolving an apparent discrepancy between the two theories. A brief d iscussion is given of how this calculation might be generalized to com pare the Matrix theory and supergravity descriptions of an arbitrary 3 -body system. (C) 1998 Published by Elsevier Science B.V. All rights r eserved.