标题： 四胶子顶点在 collinear 动量下的情况 显示英文标题

标题： Four-gluon vertex in collinear kinematics

摘要： 迄今为止，四胶子顶点是QCD拉格朗日中最少被探索的部分，主要是由于描述它需要大量的洛伦兹和颜色结构。在这项工作中，我们基于从4PI有效作用量得到的一圈着色的施温格-狄拉克方程，对该顶点进行了非微扰研究。通过采用“共线”动量分布（所有动量都相互平行）以及利用电荷共轭对称性来消除某些颜色结构，极大地简化了问题。在构成该顶点横向投影版本的十五个形式因子中，有两个被单独挑选出来并详细研究；与经典张量结构相关的那个在红外区域适度抑制，而另一个在原点处以对数方式发散。有趣的是，这两个形式因子在相当高的精度上表现出一种被称为“平面退化”的性质。根据这些结果，我们构建了一个有效的耦合常数来量化四胶子相互作用的强度，并将其与其他来自QCD规范部门的由顶点导出的耦合常数进行比较。 显示英文摘要

摘要： To date, the four-gluon vertex is the least explored component of the QCD Lagrangian, mainly due to the vast proliferation of Lorentz and color structures required for its description. In this work we present a nonperturbative study of this vertex, based on the one-loop dressed Schwinger-Dyson equation obtained from the 4PI effective action. A vast simplification is brought about by resorting to ``collinear'' kinematics, where all momenta are parallel to each other, and by appealing to the charge conjugation symmetry in order to eliminate certain color structures. Out of the fifteen form factors that comprise the transversely-projected version of this vertex, two are singled out and studied in detail; the one associated with the classical tensorial structure is moderately suppressed in the infrared regime, while the other diverges logarithmically at the origin. Quite interestingly, both form factors display the property known as ``planar degeneracy'' at a rather high level of accuracy. With these results we construct an effective charge that quantifies the strength of the four-gluon interaction, and compare it with other vertex-derived charges from the gauge sector of QCD.