We study the effect of spatial anisotropy on polar flocks by investigating active q-state clock
models in two dimensions. In contrast to the equilibrium case, we find that any amount of …

We study numerically the Toner-Tu field theory where the density field is maintained
constant, a limit case of “Malthusian” flocks for which the asymptotic scaling of correlation …

Living many-body systems often exhibit scale-free collective behavior reminiscent of thermal
critical phenomena. But their mutual interactions are inevitably retarded due to information …

We study the one-dimensional active Ising model in which aligning particles undergo
diffusion biased by the signs of their spins. The phase diagram obtained varying the density …

Flocking models with metric and topological interactions are supposed to exhibit distinct
features, as for instance the presence and absence of moving polar bands. On the other …

Flocking in d= 2 is a genuine nonequilibrium phenomenon for which irreversibility is an
essential ingredient. We study a class of minimal flocking models whose only source of …

Collective behaviors exhibited by animal groups, such as fish schools, bird flocks, or insect
swarms are fascinating examples of self-organization in biology. Concepts and methods …

We show that arbitrarily large polar flocks are susceptible to the presence of a single small
obstacle. In a wide region of parameter space, the obstacle triggers counterpropagating …

Collective motion of animal groups such as fish schools and bird flocks in three-dimensional
(3D) space are modeled by considering a topological (Voronoi) neighborhood. The …

We study the stability of the ordered phase of flocking models with a scalar order parameter.
Using both the active Ising model and a hydrodynamic description, we show that droplets of …