  We present a numerical study on non-Fermi liquid behaviour of a three
dimensional system. The Hubbard model in a cubic lattice is simulated by the
dynamical cluster approximation, in particular the quasi-particle weight is
calculated at finite dopings for a range of temperatures. Near the putative
quantum critical point, we find evidence of a separatrix at a finite doping
which separates the Fermi liquid from non-Fermi liquid as the doping increases.
Our results suggest that a marginal Fermi liquid and possibly a quantum
critical point should exist in the three dimensions interacting Fermi system.
