Toward the full short-time statistics of an active Brownian particle on the plane

Satya N. Majumdar, Baruch Meerson

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16 Scopus citations


We study the position distribution of a single active Brownian particle (ABP) on the plane. We show that this distribution has a compact support, the boundary of which is an expanding circle. We focus on a short-time regime and employ the optimal fluctuation method to study large deviations of the particle position coordinates x and y. We determine the optimal paths of the ABP, conditioned on reaching specified values of x and y, and the large deviation functions of the marginal distributions of x and of y. These marginal distributions match continuously with "near tails"of the x and y distributions of typical fluctuations, studied earlier. We also calculate the large deviation function of the joint x and y distribution P(x,y,t) in a vicinity of a special "zero-noise"point, and show that lnP(x,y,t) has a nontrivial self-similar structure as a function of x, y, and t. The joint distribution vanishes extremely fast at the expanding circle, exhibiting an essential singularity there. This singularity is inherited by the marginal x- A nd y-distributions. We argue that this fingerprint of the short-time dynamics remains there at all times.

Original languageAmerican English
Article number022113
JournalPhysical Review E
Issue number2
StatePublished - Aug 2020

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© 2020 American Physical Society.


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