How active field theories couple to external potentials

Yariv Kafri; Julien Tailleur

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arXiv · 2603.22424

How active field theories couple to external potentials

Yariv Kafri·Julien Tailleur

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Abstract

We study the simplest terms that need to be included in active field theories to couple them to external potentials. To do so, we consider active Brownian particles and implement a systematic perturbative expansion in the particle persistence time. The result is a non-trivial coupling between density and potential gradients, which accounts for the nonequilibrium features of active particles in the presence of an external potential, from boundary accumulation to far-field density modulation. We show how the method can be applied to particles interacting via pairwise forces and to spatial modulations of the propulsion speed.

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Yariv Kafri, Julien Tailleur. 2026-03-23. How active field theories couple to external potentials. https://arxiv.org/abs/2603.22424

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