Many-Body Theory of Dilute Bose-Einstein Condensates with Internal Degrees of Freedom

The Bogoliubov theory of weakly interacting bosons is generalized to Bose-Einstein condensates with internal degrees of freedom so that a single effective Hamiltonian produces various many-body ground states or metastable spin domains and the corresponding collective modes on an equal footing.Comment: 4pages, no figures, accepted for publication in Physical Review