We study the large distance behavior of a steady distribution of two Brownian
particles under external driving in a two-dimensional space. Employing a method
of perturbative system reduction, we analyze a Fokker-Planck equation that
describes the time evolution of the probability density for the two particles.
The expression we obtain shows that there exist a long range correlation
between the two particles, of 1/r2 type.Comment: 11 page