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arXiv · cond-mat/9909034

Asymmetric particle systems on R

J. Krug·J. Garcia
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Abstract

We study interacting particle systems on the real line which generalize the Hammersley process [D. Aldous and P. Diaconis, Prob. Theory Relat. Fields 103, 199-213 (1995)]. Particles jump to the right to a randomly chosen point between their previous position and that of the forward neighbor, at a rate which may depend on the distance to the neighbor. A class of models is identified for which the invariant particle distribution is Poisson. The bulk of the paper is devoted to a model where the jump rate is constant and the jump length is a random fraction $r$ of the distance to the forward neighbor, drawn from a probability density $ϕ(r)$ on the unit interval. This is a special case of the random average process of Ferrari and Fontes [El. J. Prob. 3, Paper no. 6 (1998)]. The discrete time version of the model has been considered previously in the context of force propagation in granular media [S.N. Coppersmith et al., Phys. Rev. E 53, 4673 (1996)]. We show that the stationary two-point function of particle spacings factorizes for any choice of $ϕ(r)$. Under the assumption that this implies pairwise independence, the invariant density of interparticle spacings for the case of uniform $ϕ(r)$ is found to be a gamma distribution with parameter $ν$, where $ν= 1/2$, 1 and 2 for continuous time, backward sequential and discrete time dynamics, respectively. A heuristic derivation of a nonlinear diffusion equation is presented, and the tracer diffusion coefficient is computed for arbitrary $ϕ(r)$ and different types of dynamics.

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J. Krug, J. Garcia. 1999-12-22. Asymmetric particle systems on R. https://doi.org/10.1023/a%3A1018688421856

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