Collective oscillations of the order parameter in superconductors with local pairs

Collective oscillations of the order parameter in superconductors with local singlet pairing are studied. It is shown that for an uncharged superfluid there exist oscillations with a sound spectrum, similar to the Anderson-Bogolyubov oscillations in the BCS theory. The long-range component of the Coulomb interaction included, there appears a plasma threshold in the oscillation spectrum. If, however, in addition to the narrow band where electrons make up local pairs, there is a broad conduction band, then the spectrum again becomes gapless