title: Collective motion of self-propelled particles with memory.
abstract: We show that memory, in the form of underdamped angular dynamics, is a crucial ingredient for the collective properties of self-propelled particles. Using Vicsek-style models with an Ornstein-Uhlenbeck process acting on angular velocity, we uncover a rich variety of collective phases not observed in usual overdamped systems, including vortex lattices and active foams. In a model with strictly nematic interactions the smectic arrangement of Vicsek waves giving rise to global polar order is observed. We also provide a calculation of the effective interaction between vortices in the case where a telegraphic noise process is at play, explaining thus the emergence and structure of the vortex lattices observed here and in motility assay experiments.
authors.affiliation: School of Materials Science, Japan Advanced Institute of Science and Technology, Ishikawa 923-1292, Japan.
authors.forename: Ken H
authors.initials: KH
authors.lastname: Nagai
authors.affiliation: Department of Applied Physics, Tokyo University of Science, Tokyo 125-8585, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Sumino
authors.affiliation: Departamento de Fisica, UFRPE, 52171-900 Recife, Pernambuco, Brazil.
authors.forename: Raul
authors.initials: R
authors.lastname: Montagne
authors.affiliation: Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
authors.forename: Igor S
authors.initials: IS
authors.lastname: Aranson
authors.affiliation: Service de Physique de l'Etat Condensé, CNRS UMR 3680, CEA-Saclay, 91191 Gif-sur-Yvette, France.|LPTMC, CNRS UMR 7600, Université Pierre et Marie Curie, 75252 Paris, France.|Beijing Computational Science Research Center, 3 Heqing Road, Beijing 100080, China.
authors.forename: Hugues
authors.initials: H
authors.lastname: Chaté