  The effect of a sinusoidal modulation of the interaction strength on a
fermion-pair condensate is analytically studied. The system is described by a
generalization of the coupled fermion-boson model that incorporates a
time-dependent intermode coupling induced via a magnetic Feshbach resonance.
Nontrivial effects are shown to emerge depending on the relative magnitude of
the modulation period and the relaxation time of the condensate. Specifically,
a nonadiabatic modulation drives the system out of thermal equilibrium: the
external field induces a variation of the quasiparticle energies, and, in turn,
a disequilibrium of the associated populations. The subsequent relaxation
process is studied and an analytical description of the gap dynamics is
obtained. Recent experimental findings are explained: the delay observed in the
response to the applied field is understood as a temperature effect linked to
the condensate relaxation time.
