Lagrangian approach to the dynamics of dark matter-wave solitons
We analyze the dynamics of dark matter-wave solitons on a Thomas-Fermi cloud described by the Gross-Pitaevskii equation with radial symmetry. One-dimensional, ring, and spherical dark solitons are considered, and the evolution of their amplitudes, velocities, and centers is investigated by means of a Lagrangian approach. In the case of large-amplitude oscillations, higher-order corrections to the corresponding equations of motion for the soliton characteristics are shown to be important in order to accurately describe its dynamics. The numerical results are found to be in very good agreement with the analytical predictions.