Abstract
A new kinetic theory for a particle moving in a random array of static spherical scatterers is derived. By decoupling a higher-order dynamical correlation function, a kinetic equation is obtained comprising known approximations like ring, repeated-ring theory, and their self-consistent versions and, in particular, the equivalence of a recent mode-coupling theory and self-consistent ring theory is established. Vertex corrections, as represented by a new class of collision sequences, are shown to be essential for the Lorentz gas. New results for the Burnett coefficient are also presented.