Bertin E Droz M Grégoire G 2006 We study analytically the emergence of spontaneous collective motion within large bidimensional groups of self-propelled particles with noisy local interactions, a schematic model for assemblies of biological organisms. As a central result, we derive from the individual dynamics the hydrodynamic equations for the density and velocity fields, thus giving a microscopic foundation to the phenomenological equations used in previous approaches. A homogeneous spontaneous motion emerges below a transition line in the noise-density plane. Yet, this state is shown to be unstable against spatial perturbations, suggesting that more complicated structures should eventually appear. application/pdf https://sonar.ch/global/documents/117831 eng info:eu-repo/semantics/altIdentifier/doi/10.1103/PhysRevE.74.022101 info:eu-repo/semantics/altIdentifier/pmid/17025488 info:eu-repo/semantics/openAccess Physical review. E, Statistical, nonlinear, and soft matter physics. - 2006 Boltzmann and hydrodynamic description for self-propelled particles. http://purl.org/coar/resource_type/c_6501