Dresden 2026 – scientific programme
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BP: Fachverband Biologische Physik
BP 6: Active Matter II (joint session DY/BP/CPP)
BP 6.9: Talk
Monday, March 9, 2026, 17:30–17:45, ZEU/0160
Novel Phase Coexistence in a Multi-Species Vicsek Model — •Eloise Lardet1, Letien Chen1,2, and Thibault Bertrand1 — 1Imperial College London, UK — 2University of Edinburgh, UK
A hallmark in natural systems, self-organization often stems from very simple interaction rules between individual agents. While single-species self-propelled particle (SPP) systems are well understood, the behavior of mixtures of self-propelled particles with general alignment interactions remains largely unexplored with a few scattered results hinting at the existence of a rich emergent phase behavior. Here, we first present a generalization of the two-species Vicsek model with reciprocal intra- and interspecies (anti-)alignment couplings, uncovering a rich phenomenology of emergent states. Notably, we show that rather than destroying polar order, anti-aligning interactions can promote phase separation and the emergence of global polar order. Secondly, we derive a kinetic theory for the system, finding good agreement between theoretical predictions and particle simulations. This includes a novel mechanism for microphase separation, as predicted by a Turing instability. We finally show that these coexistence patterns can be generalized to multi-species systems with cyclic alignment interactions.
Keywords: Flocking; Vicsek; Phase separation; Species interactions; Kinetic theory