Abstract
We start from quantum chromodynamics in a finite volume of linear size L and examine its color-dielectric constant κL, especially the limit κ∞ as L→∞. By choosing as our standard κL=1 when L=somehadronsize R, we conclude that κ∞ must be κ∞<1.3×10−2α where α is the fine-structure constant of QCD inside the hadron. A permanent quark confinement corresponds to the limit κ∞=0. The hadrons are viewed as small domain structures (with color-dielectric constant = 1) immersed in a perfect, or nearly perfect, color-dia-electric medium, which is the vacuum. The Feynman rules of QCD inside the hadron are derived; they are found to depend on the color-dielectric constant κ∞ of the vacuum that lies outside. We show that, when κ∞→0, the mass of any color-nonsinglet state becomes ∞, but for color-singlet states their masses and scattering amplitudes remain finite. These new Feynman rules also depend on the hadron size R. Only at high energy and large four-momentum transfer can such R dependence be neglected and, for color-singlet states, these new rules be reduced to the usual ones.