标题： 自发破缺的$(-1)$-形式 U(1) 对称性 显示英文标题

标题： Spontaneously Broken $(-1)$-Form U(1) Symmetries

摘要： 对称性的自发破缺会导致普遍现象。 我们将这一概念扩展到$(-1)$-形式的U(1)对称性。 通过真空能量对常数背景场$\theta$的依赖性可以诊断出自发破缺，而后者可以通过拓扑易感性来探测。 这导致了强CP问题被重新解释为源自QCD中的自发破缺瞬子对称性。 我们讨论了在此框架下已知解决方案如何统一，并探讨了一些迄今未成功的寻找新解决方案的尝试。 显示英文摘要

摘要： Spontaneous breaking of symmetries leads to universal phenomena. We extend this notion to $(-1)$-form U(1) symmetries. The spontaneous breaking is diagnosed by a dependence of the vacuum energy on a constant background field $\theta$, which can be probed by the topological susceptibility. This leads to a reinterpretation of the Strong CP problem as arising from a spontaneously broken instantonic symmetry in QCD. We discuss how known solutions to the problem are unified in this framework and explore some, so far unsuccessful, attempts to find new solutions.