LOW-ENERGY SCATTERING OF SOLITONS IN THE CP1 MODEL

The interactions of slowly moving lump-like solitons in the (2 + 1)-dimensional CP1 model are investigated, using an approximation in which the evolution is given by geodesic motion on the manifold of static solutions. Some special geodesics are identified analytically, while others are calculated numerically. The fact that the model is conformally invariant means that the lumps may change size as they move, and this in turn gives rise to a particularly rich structure; for example, some interactions lead to infinitely tall spikes. In the simplest head-on collisions, solitons scatter at right angles to their original direction of motion. For nonzero impact parameters, the scattering angle is less than 90°, gradually approaching zero as the impact parameter becomes very large. However, a carefully chosen initial squashing can "absorb" the forces of repulsion that would otherwise be present. A further feature is the existence of an internal phase, which, if excited, can produce a whole range of scattering angles, even in a head-on collision. © 1990.