  Motivated by recent experiment on the Na$_4$Ir$_3$O$_8$ compound we study the
Hubbard model on the "hyper-kagome lattice", which forms a three-dimensional
network of corner sharing triangles, using dynamical cluster approximation
(DCA) method with $N_c$=12 combined with the continuous-time quantum Monte
Carlo (CT QMC) method. The system undergoes a Mott transition if the Hubbard
interaction $U/W$ ($W$ is the bandwidth) exceeds the value of 1.2 for $T$=0.1
and displays reentrant behavior due to competition between the magnetic
correlation and the kinetic energy of electrons due to the geometrical
frustration. We observe a "critical slowing down" of the double occupancy which
shows evidence of a continuous transition. The nearest-neighbor and next
nearest-neighbor spin-spin correlations indicate a paramagnetic metallic state
in the weak-coupling regime and an antiferromagnetic (AF) Mott insulator in the
strong-coupling regime within the temperature range which we can access with
our numerical tools.
