Brownian particle in ideal gas: explicit density expansions, conditional   probabilities, and amusing properties of molecular chaos
  Explicit density expansions of non-equilibrium probability distribution functions for molecular Brownian particle in ideal gas are obtained in original form what visually implies (is exact solution to) the previously established dynamical virial relations. Role of these relations in unbiased analysis of molecular chaos properties in many-particle statistical mechanics, including the mobility 1/f noise, is newly investigated in clear terms of conditional probabilities and averages. 
Yu.E.Kuzovlev
cond-mat.stat-mech physics.class-ph