标题： 强CP问题，θ项和QCD拓扑性质 显示英文标题

标题： Strong CP problem, theta term and QCD topological properties

摘要： 在本章中，我们介绍$\theta$依赖性和QCD的拓扑性质，这些是强相互作用部分的特征，在粒子物理的标准模型更广泛的背景下导致了强CP问题。 我们讨论可以用来获得QCD和类QCD模型的$\theta$依赖性的定性信息，或在某些情况下定量信息的分析方法，讨论它们的有效范围，并将它们的预测与通过格点模拟获得的数值结果进行比较。 显示英文摘要

摘要： In this chapter we introduce the $\theta$-dependence and the topological properties of QCD, features of the strongly interacting sector which give rise to the strong CP problem in the more general context of the Standard Model of particle physics. We discuss the analytical approaches that can be used to obtain qualitative, or in some cases quantitative, information on the $\theta$-dependence of QCD and QCD-like models, discussing their range of validity and comparing their predictions with the numerical results obtained by means of lattice simulations.