Dresden 2026 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 17: Active Matter II (joint session DY/BP/CPP)
DY 17.11: Talk
Monday, March 9, 2026, 18:00–18:15, ZEU/0160
Collective behavior in nonreciprocal multi-species Vicsek model with permutation symmetry — •Jae Dong Noh1, Chul-Ung Woo2, and Heiko Rieger2 — 1Department of Physics, University of Seoul, Seoul 02504, Korea — 2Department of Theoretical Physics and Center for Biophysics, Saarland University, Saarbrücken, Germany
Nonreciprocal systems are typically built upon asymmetric roles 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 from an asymmetric coupling matrix. This system displays rich collective behaviors, including a species-mixed chiral phase with quasi-long-range polar order and a species-separated vortex cell phase. We present numerical evidence for these phases using particle-based Monte Carlo simulations and analytic evidence using continuum Boltzmann and hydrodynamic equations. Our work demonstrates that multi-species chiral fluids can be realized by a nonreciprocal but symmetric alignment interaction, where the rich collective behavior is a consequence of the interplay between nonreciprocity and permutation symmetry.
Keywords: multi-species Vicsek model; nonreciprocity; permutation symmetry; chirality; species separation