Ja n 19 94 Color Confinement , Quark Pair Creation and Dynamical Chiral - Symmetry Breaking in the Dual Ginzburg - Landau Theory

We study the color confinement, the q-¯ q pair creation and the dynamical chiral-symmetry breaking of nonperturbative QCD by using the dual Ginzburg-Landau theory, where QCD-monopole condensation plays an essential role on the nonper-turbative dynamics in the infrared region. As a result of the dual Meissner effect, the linear static quark potential, which characterizes the quark confinement, is obtained in the long distance within the quenched approximation. We obtain a simple expression for the string tension similar to the energy per unit length of a vortex in the superconductivity physics. The dynamical effect of light quarks on the quark confining potential is investigated in terms of the infrared screening effect due to the q-¯ q pair creation or the cut of the hadronic string. The screening length of the potential is estimated by using the Schwinger formula for the q-¯ q pair creation. We introduce the corresponding infrared cutoff to the strong long-range correlation factor in the gluon propagator as a dynamical effect of light quarks, and obtain a compact formula of the quark potential including the screening effect in the infrared region. We investigate the dynamical chiral-symmetry breaking by using the Schwinger-Dyson equation, where the gluon propagator includes the non-perturbative effect related to the color confinement. We find a large enhancement of the chiral-symmetry breaking when the dual Meissner effect takes place, which supports the close relation between the color confinement and the chiral-symmetry breaking. The dynamical quark mass, the pion decay constant and the quark con-densate are well reproduced by using the consistent values of the gauge coupling constant and the QCD scale parameter with the perturbative QCD and the quark confining potential. The confinement of light quarks is also investigated by the smooth extrapolation of the quark mass function to the time-like momentum region. We find the disappearance of physical poles in the light-quark propagator, and show the confinement of light quarks in the dual Ginzburg-Landau theory.