  We use the non-equilibrium bosonization technique to investigate effects of
the Coulomb interaction on quantum Hall edge states at filing factor nu=2,
partitioned by a quantum point contact (QPC). We find, that due to the
integrability of charge dynamics, edge states evolve to a non-equilibrium
stationary state with a number of specific features. In particular, the noise
temperature of a weak backscattering current between edge channels is linear in
voltage bias applied at the QPC, independently of the interaction strength. In
addition, it is a non-analytical function of the QPC transparency T and scales
as Tln(1/T) at T<< 1. Our predictions are confirmed by exact numerical
calculations.
