论文标题
强$ CP $问题的限制
The limits of the strong $CP$ problem
论文作者
论文摘要
尽管在强烈的互动中从未观察到$ cp $违规行为，但QCD拉格朗日人承认与所谓的$θ$角度成正比的$ CP $ -ODD拓扑交互，这使来自不同拓扑领域的分区功能的贡献权重。观察界通常被解释为要求$θ$对夸克群体的阶段进行严重调整，这构成了强大的$ cp $问题。在这里，我们根据对路径积分中边界条件的仔细处理和无限时空量的限制的仔细处理，对这种观点的最新挑战进行了报道，这导致$θ$从费米昂相关功能中删除并变得无法观察到，这意味着$ cp $保留在QCD中。
While $CP$ violation has never been observed in the strong interactions, the QCD Lagrangian admits a $CP$-odd topological interaction proportional to the so called $θ$ angle, which weighs the contributions to the partition function from different topological sectors. The observational bounds are usually interpreted as demanding a severe tuning of $θ$ against the phases of the quark masses, which constitutes the strong $CP$ problem. Here we report on recent challenges to this view based on a careful treatment of boundary conditions in the path integral and of the limit of infinite spacetime volume, which leads to $θ$ dropping out of fermion correlation functions and becoming unobservable, implying that $CP$ is preserved in QCD.
