The transport properties of the quark-gluon plasma is important both from the point of view of the astrophysical systems and the heavy ion collisions. Therefore, accurate calculations of the elastic scattering cross-sections of $qq' \to qq'$ and $ q\qbar' \to q\qbar'$ processes are required. At the tree-diagram level exchange of massless gluons leads to divergent cross sections for such processes. An effective way to remove the infrared divergence is to introduce a Debye mass as an infrared regulator into the gluon propagator for the thermal gluons. In this work we find that at the two-gluon exchange level such a technique fails to remove the divergences. In a chiral symmetry broken phase the mass could be introduced following the standard procedure which cures the divergence. But in a chirally symmetric phase chiral invariant mass of the fermions needs to be considered.
翻译:从天体物理学系统和重离子碰撞的角度来看,夸克-格鲁翁等离子体的迁移特性都很重要。 因此, 需要精确计算 $qq' $to qq' $ 和 qqqbar' $ qqqqbar $ qqqqqqbar 的弹性散射剖面。 在无质量凝胶的树- 直角水平交换导致这种过程的交叉部分差异。 消除红外线差异的有效方法是将一个Debye质量作为红外线调节器引入热凝胶的凝胶推进器。 在这项工作中, 我们发现在两个格交换层的这种技术无法消除差异。 在一个对称性断裂的阶段, 质量可以按照治疗差异的标准程序引入。 但是, 在一个对等相相相的阶段, 需要考虑发热力质量的变异性质量。