  We present the general kinetic formalism for the description of spin and
energy relaxation of the cavity polaritons in the framework of the Born-Markov
approximation. All essential mechanisms of polaritons redistribution in
reciprocal space together with final state bosonic stimulation are taken into
account, from our point of view. The developed theory is applied to describe
our experimental results on the polarization dynamics obtained in the polariton
parametric amplifier geometry (pumping at so-called magic angle). We have
experimentally confirmed that the anisotropy of the polariton-polariton
interaction is responsible for the build up of the cross-linear polarisation of
the signal. The long-living linear polarization is observed at zero detuning.
Under elliptical pumping, we have directly measured in the time domain and
modelled the effect of self-induced Larmor precession.
