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arXiv · 1507.00484

Distribution of the position of a driven tracer in a hardcore lattice gas

Pierre Illien·Olivier Bénichou·Gleb Oshanin·Raphaël Voituriez
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Abstract

We study the position of a biased tracer particle (TP) in a bath of hardcore particles moving on a lattice of arbitrary dimension and in contact with a reservoir. Starting from the master equation satisfied by the joint probability of the TP position and the bath configuration and resorting to a mean-field-type approximation, we presented a computation of the fluctuations of the TP position in a previous publication [Phys. Rev. E \textbf{87}, 032164 (2013)]. Counterintuitively, on a one-dimensional lattice, the diffusion coefficient of the TP was shown to be a non-monotonic function of the density of bath particles, and reaches a maximum for a nonzero value of the density. Here, we: (i) give the details of this computation and offer a physical insight into the understanding of the non-monotonicity of the diffusion coefficient; (ii) extend the mean-field-type approximation to decouple higher-order correlation functions, and obtain the evolution equation satisfied by the cumulant generating function of the position of the TP, valid in any space dimension. In the particular case of a one-dimensional lattice, we solve this equation and obtain the probability distribution of the TP position. We show that the position rescaled by its fluctuations is asymptotically distributed accordingly to a Gaussian distribution in the long-time limit.

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Pierre Illien, Olivier Bénichou, Gleb Oshanin, Raphaël Voituriez. 2015-07-02. Distribution of the position of a driven tracer in a hardcore lattice gas. https://doi.org/10.1088/1742-5468/2015/11/p11016

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