Dynamical Chiral Symmetry Breaking in the Multi-Instanton Vacuum of QCD

We study the properties of SU(N_f) light quarks in the multi-instanton vacuum of QCD. We formulate the dynamical symmetry breaking for light quarks of various numbers of flavor N_f with the inclusion of the instanton size distribution. We find that the quark mass function increases rapidly toward small Euclidean momenta when the finite size distribution is introduced with a power law fall-off of large instanton size, ρ^-n (n > 3). We observe a confining feature of light quarks for small fall-off parameter n and for large packing fraction bar {ρ }/bar {R} in the behavior of the quark mass function extrapolated to the time-like region.