Behavior of Gluons at non-perturbative region and Confinement Mechanism

夸克和胶子是QCD的两种成分，它的显著特征是禁闭。尽管胶子传播子不是物理可观测的，但它们是作为量子场论的QCD中的一个基本对象。它们的长距离行为可能揭示了胶子限制机制的线索。Gribov发现标准规范固定条件不足以在非阿贝尔规范理论的规范等价条件中选择单一的组态。我们利用Zwanziger的随机规范对胶子传播子进行了数值计算，保证了我们在Gribov区域。随着tau的增加，胶子会出现很大的偏差；当tau较大时，胶子似乎变得很大。在中间区域，推进器的形状是凸起的。如果我们将行为解释为Maass极点之和，则谱函数不可能是正定的，即存在负范数态的混合。有效质量在很大的tau时似乎消失了，尽管误差条很大。这一结果可以用Gribov猜想进行定量拟合，但不能进行定量拟合。

Quarks and gluons are two ingredients of QCD,whose prominent character is the confinement. Although they are not physical observables, gluon propagators are a fundamentaal object in QCD as a quantum field theory. Their long distance behavior may reveal a hint of the gluon confinement mechanism. Gribov found that standard gauge fixing conditions are not enough to select a single cofiguration among gauge equivalent ones for non-Abelian gauge theories.We calculate gluon propagators numerically by using Zwanziger's stochastic gauge which guarantees that we are in the Gribov region. Large deviation appears as tau increases ; the gluon seems to become massive at large tau. At intermediate region, the shape of the propgator is convex to the above. If we would interpret the behavior as the sum of maass poles, the spectral function can not be positive definite, i.e., there is an admixture of negative norm states. The effective mass seems to vanish at very large tau, although there error bars are very large. The result can be quantitatively fit by Gribov conjecture, but not quantitatively.