Continuous Theory of Active Matter Systems with Metric-Free Interactions

Anton Peshkov, Sandrine Ngo, Eric Bertin, Hugues Chate, Francesco Ginelli

Research output: Contribution to journalArticlepeer-review

63 Citations (Scopus)


We derive a hydrodynamic description of metric-free active matter: starting from self-propelled particles aligning with neighbors defined by "topological" rules, not metric zones-a situation advocated recently to be relevant for bird flocks, fish schools, and crowds-we use a kinetic approach to obtain well-controlled nonlinear field equations. We show that the density-independent collision rate per particle characteristic of topological interactions suppresses the linear instability of the homogeneous ordered phase and the nonlinear density segregation generically present near threshold in metric models, in agreement with microscopic simulations.

Original languageEnglish
Article number098101
Number of pages6
JournalPhysical Review Letters
Issue number9
Publication statusPublished - 28 Aug 2012


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