The non-Gaussian tops and tails of diffusing boomerangs
Royal Society of Chemistry
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Koens, L. M., Lisicki, M., & Lauga, E. L. (2017). The non-Gaussian tops and tails of diffusing boomerangs. Soft Matter, 13 (16), 2977-2982. https://doi.org/10.1039/c6sm02649d
Experiments involving the two-dimensional passive diffusion of colloidal boomerangs tracked off their centre of mobility have shown striking non-Gaussian tails in their probability distribution function [Chakrabarty et al., Soft Matter, 2016, 12, 4318]. This in turn can lead to anomalous diffusion characteristics, including mean drift. In this paper, we develop a general theoretical explanation for these measurements. The idea relies on calculating the two-dimensional probability densities at the centre of mobility of the particle, where all distributions are Gaussian, and then transforming them to a different reference point. Our model clearly captures the experimental results, without any fitting parameters, and demonstrates that the one-dimensional probability distributions may also exhibit strongly non-Gaussian tops. These results indicate that the choice of tracking point can cause a considerable departure from Gaussian statistics, potentially causing some common modelling techniques to fail.
This research was funded in part by an ERC grant to EL and a Mobility Plus Fellowship from the Polish Ministry of Science and Higher Education to ML.
ECH2020 EUROPEAN RESEARCH COUNCIL (ERC) (682754)
External DOI: https://doi.org/10.1039/c6sm02649d
This record's URL: https://www.repository.cam.ac.uk/handle/1810/265180