The problem of the dynamics of the phase transition in an interacting Bose system is investigated from a microscopic point of view. By a general analysis of the structure of the perturbation expansion the existence of certain poles in the self-energies and the polarization part is revealed, which offers a mechanism to separate the one-particle and collective spectra (coinciding all over the Bose condensation range) from each other at the phase transition point. As an illustration to the general method mentioned above the model of the weakly interacting Bose gas is worked out in detail. The model possesses two excitation branches: One of them, the critical mode, exhibits universality and scaling behavior, if the system is close enough to the transition point.
ASJC Scopus subject areas
- Physics and Astronomy(all)