  We formulate a simple harmonic mean-field model with N+1 particles and
analyse the relaxation processes following a jump of one of these particles.
Either the particle can jump back (single-particle route) or the other N
particles adjust themselves (multi-particle route). The dynamics of this model
is solved analytically in the linear response regime. Furthermore we relate
these results to a phenomenological approach by Funke and coworkers (concept of
mismatch and relaxation: CMR) which has been successfully used to model
conductivity spectra in the field of ion dynamics in solid electrolytes. Since
the mean-field model contains the relevant ingredients of the CMR-approach, a
comparison of the resulting rate equations with the CMR-equations becomes
possible. Generalizations beyond the mean-field case are discussed.
