Changing shapes: adiabatic dynamics of composite solitary waves
  We discuss the solitary wave solutions of a particular two-component scalar field model in two-dimensional Minkowski space. These solitary waves involve one, two or four lumps of energy. The adiabatic motion of these composite non-linear non-dispersive waves points to variations in shape. 
A. Alonso Izquierdo, M.A. Gonzalez Leon, M. de la Torre Mayado and J.   Mateos Guilarte