  Via the hierarchy of correlations, we study the Mott insulator phase of the
Fermi-Hubbard model in the limit of strong interactions and derive a quantum
Boltzmann equation describing its relaxation dynamics. In stark contrast to the
weakly interacting case, we find that the scattering cross sections strongly
depend on the momenta of the colliding quasi-particles and holes. Therefore,
the relaxation towards equilibrium crucially depends on the spectrum of
excitations. For example, for particle-hole excitations directly at the minimum
of the (direct) Mott gap, the scattering cross sections vanish such that these
excitations can have a very long life-time.
