Eleven-dimensional massless superparticles and matrix theory spin-orbit couplings reexamined

Abstract

The classical probe dynamics of the 11-dimensionaI massless superparticles in the background geometry produced by N source M-momenta is investigated in the framework of N-sector DLCQ supergravity. We expand the probe action up to two fermion terms and find that the fermionic contributions are the spin-orbit couplings, which precisely agree with the matrix theory calculations. We comment on the lack of nonperturbative corrections in the one-loop matrix quantum mechanics effective action and its compatibility with the supergravity analysis. [S0556-2821(99)10218-2].