Large-Flavor QCD on the Lattice

Abstract

We study the nature of the QCD vacuum at general number of flavors $N_F$ by numerical simulations on the lattice. Combining the results with those of the perturbation theory, we propose the following picture: 1) For $N_F\ge 17$, there exists only one IR fixed point at vanishing gauge coupling, i.e., the theory in the continuum limit is trivial. 2) For $16\ge N_F\ge 7$, there is a non-trivial fixed point. Therefore, the theory is non-trivial with anomalous dimensions, however, without quark confinement. 3) For $N_F\le 6$, theories satisfy both quark confinement and spontaneous chiral symmetry breaking in the continuum limit.

15 pages, 13 figures. Talk presented by K. Kanaya at the TMU-Yale Symposium on Dynamics of Gauge Fields, Dec.13--15, 1999, Hachioji, Japan