Dynamics of nontopological solitons: Q balls

We use numerical simulations and semianalytical methods to investigate the stability and the interactions of nontopological stationary Q ball solutions. In the context of a simple model we map the parameter sectors of stability for a single Q ball and verify the result using numerical simulations of time evolution. The system of two interacting Q balls is also studied in one and two space dimensions. We find that the system generically performs breather-type oscillations with frequency equal to the difference of the internal Q ball frequencies. This result is shown to be consistent with the form of the Q ball interaction potential. Finally we perform simulations of Q ball scattering and show that the right angle scattering effect observed in topological soliton scattering in two dimensions persists also in the case of Q balls where no topologically conserved quantities are present. For relativistic collision velocities the Q ball charge is split into a forward and a right angle scattering component. As the collision velocity increases, the forward component gets amplified at the expense of the right angle component.