QUANTUM CHROMODYNAMICS WITH MANY FLAVORS

We investigate the phase structure of lattice QCD for general number o f flavors N-F. On the basis of numerical data combined with the result s of the perturbation theory we propose the following picture: When N- F greater than or equal to 17, there is only one IR fixed point at van ishing gauge coupling, i.e., the theory in the continuum limit is triv ial. On the other hand, when 16 greater than or equal to N-F greater t han or equal to 7, there is a non-trivial fixed point. Therefore, the theory is non-trivial with anomalous dimensions, however, without quar k confinement. Theories which satisfy both quark confinement and spont aneous chiral symmetry breaking in the continuum limit exist only for N-F less than or equal to 6.