Journal of Statistical Physics, Vol. 99, Nos. 34, 2000. p. 1045-1049.
We study tracer diffusion in the continuous-time asymmetric random average process which is an interacting particle system on R generalizing the Hammer-sley process. From the equations of motion for the particle-position correlations we obtain the exact tracer diffusion coefficient which is in agreement with a recent heuristic result by Krug and Garcia.