Critical behavior in (2+1)-dimensional QCD.

Abstract

QCD in 2+1 dimensions with N species of fermions, analyzed in the 1/N expansion, is shown to exhibit a chiral and confinement phase transition as N approaches a critical value ${\mathrm{N}}_{\mathrm{c}}$. For N>${\mathrm{N}}_{\mathrm{c}}$, the theory is chirally symmetric and deconfined. For N${\mathrm{N}}_{\mathrm{c}}$, chiral symmetry is broken and confinement sets in at momentum scales less than the fermion mass. The reliability of the 1/N expansion when N\ensuremath{\simeq}${\mathrm{N}}_{\mathrm{c}}$ is discussed, and the behavior of this theory is contrasted with QCD in 3+1 dimensions.