Dynamical Model of QCD Vacuum and Quark Confinement

The phase transition of a simple local gauge model is investigated in termsof the Nambu-Jona-Lasinio mechanism and it is pointed out that thephysical vacuum of QCD is bound state of quark-antiquark pairs which can beviewed, generally, as a nearly perfect color dia-electric medium. Animportant relation between the vacuum expectation value of gauge fields andscalar fields is also derived by solving the Euler equation for the gaugefields. Based on this relation the SU_C(3) gauge potential is given which can be used to explain the asymptotic behavior and confinement of quarks in a hadron, and at the same time the Yukawa potential of strong interaction can be given too.