  We continue to study out of equilibrium TFT with switching on the interaction
occurring at finite time. We exploit the concept of projected function (PF) and
Wigner transform of projected function (WTPF). WTPF's are bare propagators,
one-loop self-energies, retarded and advanced components of the resummed
propagator. Among WTPF's convolution product is very simple, one does not need
gradient expansion. However, WTPF's are completely determined by their infinite
time limit and, thus, cannot be the carriers of relaxation phenomena.
Furthermore, we observe that the functions capable of carrying relaxation
phenomena (non-WTPF) emerge in the mixed ("ill-defined") products of retarded
and advanced propagators and self-energies. In particular, only non-WTPF's
contribute to time variation of equal-time Green functions (particle number,
etc.); contributions from WTPF will be constant in time. As these are generated
in mixed products, the pinching phenomenon is being promoted from an obstacle
to the central feature of out of equilibrium TFT. We analyze the pinching
phenomenon. In the case of naive pinching we reproduce known results. In
Schwinger-Dyson equations the Keldysh component of self-energy is well defined
even for multiple self-energy insertion contributions. We calaculate explicitly
single self-energy contribution to Keldysh component of propagator which
generates nontrivial time dependence. For photon production from QCD plasma
(finite-lifetime effect) our approximate analytic results agree with the
results by S. -Y. Wang and D. Boyanovsky obtained within dynamical
renormalisation group approach.
