Emergent spatial structures in flocking models: a dynamical system   insight
  We show that hydrodynamic theories of polar active matter generically possess inhomogeneous traveling solutions. We introduce a unifying dynamical-system framework to establish the shape of these intrinsically nonlinear patterns, and show that they correspond to those hitherto observed in experiments and numerical simulations: periodic density waves, and solitonic bands, or polar-liquid droplets both cruising in isotropic phases. We elucidate their respective multiplicity and mutual relations, as well as their existence domain. 
Jean-Baptiste Caussin, Alexandre Solon, Anton Peshkov, Hugues Chat\'e,   Thierry Dauxois, Julien Tailleur, Vincenzo Vitelli,...
cond-mat.soft