Phase Structure of Lattice Qcd for General Number of Flavors

We investigate the phase structure of lattice QCD for general number of flavors NF . Based on numerical results combined with the result of the perturbation theory we propose the following picture: When NF ≥ 17, there is only a trivial fixed point and therefore the theory in the continuum limit is trivial. On the other hand, when 16 ≥ NF ≥ 7, there is a non-trivial fixed point and therefore the theory is nontrivial with anomalous dimensions, however, without quark confinement. Theories which satisfy both quark confinement and spontaneous chiral symmetry breaking in the continuum limit exist only for NF ≤ 6.