Kinetics of self-induced aggregation in Brownian particles.

We study a model of interacting random walkers that proposes a simple mechanism for the emergence of cooperation in a group of individuals. Each individual, represented by a Brownian particle, experiences an interaction produced by the local unbalance in the spatial distribution of the other individuals. This interaction results in a nonlinear velocity driving the particle trajectories in the direction of the nearest more crowded region; the competition among different aggregating centers generates nontrivial dynamical regimes. Our simulations show that for sufficiently low randomness the system evolves through a coalescence behavior characterized by clusters of particles growing with a power law in time. In addition, the typical scaling properties of the general theory of stochastic aggregation processes are verified.