Motion of Coloured Particles in Solitons of the O(3) Non-Linear Model
  We propose a consistent expression for the relativistic quadri-force referring to the classical interaction between a coloured particle and a scalar field multiplete. General aspects of the resultant equations of motion are discussed as well as a specialisation to the case of a SU(2) particle in the presence of a soliton configuration of the non-linear O(3) model with unit topological charge. Analytical studies regarding the stability and asymptotic behaviour of this system are made and extended to the case of arbitrary topological charge. Since the non-linear O(3) model describes an isotropic ferromagnet, we also investigate a possible physical interpretation of such a system. 
Rafael M. Fernandes and Patricio S. Letelier