NOVEL TYPE OF PHASE-TRANSITION IN A SYSTEM OF SELF-DRIVEN PARTICLES

A simple model with a novel type of dynamics is introduced in order to investigate the emergence of self-ordered motion in systems of partic les with biologically motivated interaction. In our model particles ar e driven with a constant absolute velocity and at each time step assum e the average direction of motion of the particles in their neighborho od with some random perturbation (eta) added. We present numerical evi dence that this model results in a kinetic phase transition from no tr ansport (zero average velocity, \v(a)\ = 0) to finite net transport th rough spontaneous symmetry breaking of the rotational symmetry. The tr ansition is continuous, since \v(a)\ is found to scale as (eta(c) - et a)(beta) with beta similar or equal to 0.45.