Nonreciprocal solitons as  a model for information transfer in flocks

Motivated by the fact that a flock of birds naturally breaks spatial symmetry when flying. This model introduces active torques able to generate nonreciprocity in a set of rotating spins. Moreover, since the mutual torque interaction between spins is usually considered as a sine function; this naturally leads to a cosine potential that under moderate rotations may be represented as a quartic one. This nonlinear potential naturally leads in the continuum limit to a nonlinear nonreciprocal mKdV equation for the rotational degree of freedom. The effects of this model are analyzed.