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arXiv · 2512.18749

Nonreciprocal yet Symmetric Multi-Species Active Matter: Emergence of Chirality and Species Separation

Chul-Ung Woo·Heiko Rieger·Jae Dong Noh
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Abstract

Nonreciprocal active matter systems typically feature an asymmetric role among interacting agents, such as a pursuer-evader relationship. We propose a multi-species nonreciprocal active matter model that is invariant under permutations of the particle species. The nonreciprocal, yet symmetric, interactions emerge from a constant phase shift in the velocity alignment interactions, rather than from an asymmetric coupling matrix. This system possessing permutation symmetry displays rich collective behaviors, including a species-mixed chiral phase with quasi-long-range polar order and a species separation phase characterized by vortex cells. The system also displays a coexistence phase of the chiral and the species separation phases, in which intriguing dynamic patterns emerge. These rich collective behaviors are a consequence of the interplay between nonreciprocity and permutation symmetry.

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Chul-Ung Woo, Heiko Rieger, Jae Dong Noh. 2025-12-21. Nonreciprocal yet Symmetric Multi-Species Active Matter: Emergence of Chirality and Species Separation. https://arxiv.org/abs/2512.18749

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