Spin-dependent polariton-polariton scattering in planar microcavities

We present a microscopic theory of polariton-polariton (PP) scattering in quantum microcavities, which is developed with allowance for the composite nature of polaritons. Analytical estimations of the effective scattering rate for PP scattering with parallel spin configuration are presented, and the role of dark excitons in the opposite spin configuration is discussed.