Number fluctuations distinguish different self-propelling dynamics

Tristan Cerdin; Sophie Marbach; Carine Douarche

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arXiv · 2604.02872

Number fluctuations distinguish different self-propelling dynamics

Tristan Cerdin·Sophie Marbach·Carine Douarche

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Abstract

In nonequilibrium suspensions, static number fluctuations $N$ in virtual observation boxes reveal remarkable structural properties, but the dynamic potential of $N(t)$ signals remains unexplored. Here, we develop a theory to learn the dynamical parameters of self-propelled particle models from $N(t)$ statistics. Unlike traditional trajectory analysis, $N(t)$ statistics distinguish between models, by sensing subtle differences in reorientation dynamics that govern re-entrance events in boxes. This paves the way for quantifying advanced dynamic features in dense nonequilibrium suspensions.

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Tristan Cerdin, Sophie Marbach, Carine Douarche. 2026-04-03. Number fluctuations distinguish different self-propelling dynamics. https://arxiv.org/abs/2604.02872

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