Spin dependent D-brane interactions and scattering amplitudes in matrix theory

Spin interactions between two moving Dp-branes are analyzed using the GreenSchwarz formalism of boundary states. This approach turns out to be extremely efficient to compute all the spin effects related by supersymmetry to the leading v4/r7−p term. All these terms are shown to be scale invariant, supporting a matrix model description of supergravity interactions. By employing the LSZ reduction formula for matrix theory and the mentioned supersymmetric potential for D0-branes, we compute the t-pole of graviton-graviton and three formthree form scattering in matrix theory. The results are found to be in complete agreement with tree level supergravity in the corresponding kinematical regime and provide, moreover, an explicit map between these degrees of freedom in both theories.