COLOR CONFINEMENT, QUARK PAIR CREATION AND DYNAMICAL CHIRAL-SYMMETRY BREAKING IN THE DUAL GINZBURG-LANDAU THEORY

We study the color confinement, the q $$($) over bar q pair creation and the dynamical chiral-symmetry breaking of nonperturbative QCD by using the dual Ginzburg-Landau theory, where the dual Higgs mechanism plays an essential role in the nonperturbative dynamics in the infrared region. As a result of the dual Meissner effect, the linear static quark potential, which characterizes the quark confinement, is obtained in the long distance within the quenched approximation. We obtain a simple expression for the string tension similar to the energy per unit length of a vortex in the superconductivity physics. The dynamical effect of light quarks on the quark confining potential is investigated in terms of the infrared screening effect due to the q $$($) over bar 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 $$($) over bar 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 for the quark potential including the screening effect in the infrared region. We investigate the dynamical chiral-symmetry breaking by using the Schwinger-Dyson equation in the dual Ginzburg-Landau theory, where the gluon propagator includes the nonperturbative effect related to the color confinement. We find a large enhancement of the chiral-symmetry breaking by the dual Higgs mechanism, 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 condensate 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 light-quark confinement is also roughly examined in terms of the disappearance of physical poles in the light-quark propagator by using the smooth extrapolation of the quark mass function to the time-like momentum region.