We study the zero-temperature dynamics of Bose-Einstein condensates in driv
en high-quality optical cavities in the limit of large atom-field detuning
in a one-dimensional model. We calculate the stationary ground state and th
e spectrum of coupled atom and field mode excitations for standing-wave cav
ities as well as for traveling-wave cavities. Finite cavity response times
lead to damping or controlled amplification of these excitations. Analytic
solutions in the Lamb-Dicke expansion are in good agreement with numerical
results for the full problem and show that oscillation frequencies and the
corresponding damping rates are qualitatively different for the two cases.