Alberto Alonso Izquierdo

Solitary Waves in Massive Nonlinear S N -Sigma Models ?

The solitary waves of massive (1+1)-dimensional nonlinear S N -sigma models are unveiled. It is shown that the solitary waves in these systems are in one-to-one correspon- dence with the separatrix trajectories in the repulsive N-dimensional Neumann mechanical problem. There are topological (heteroclinic trajectories) and non-topological (homoclinic trajectories) kinks. The stability of some embedded sine-Gordon kinks is discussed by means of the direct estimation of the spectra of the second-order fluctuation operators around them, whereas the instability of other topological and non-topological kinks is established applying the Morse index theorem.