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关于 $\theta$ 和电偶极矩的一些思考

A few thoughts on $θ$ and the electric dipole moments

Ariel Zhitnitsky

备注：
6 pages. arXiv admin note: text overlap with arXiv:1702.00012
发表信息：
Phys Rev D 108 (2023) 076021
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AI总结：

本文探讨了 $\theta$ 参数对偶极矩的贡献，指出 $\theta_{QED}$ 在特定条件下可观测，并论证其会诱导电偶极矩及 CP 关联，挑战传统观点。

摘要：

我重点阐述关于所谓的 $\theta$ 参数对偶极矩贡献的一些思考。已知偶极矩可由 $\theta$ 产生。事实上，著名的强 $\cal{CP}$ 问题正是由于未观测到偶极矩而被提出的。鲜为人知的是，理论中还存在另一个参数 $\theta_{QED}$，当满足某些条件时，它也会成为系统的物理且可观测的参数。这一论断应与传统的（且非常天真的）观点形成对比，即 $\theta_{\rm QED}$ 是非物理且不可观测的。这种现象的一个具体表现是所谓的维滕效应，即磁单极子变成带有感应电荷 $e'=-e \frac{\theta_{QED}}{2\pi}$ 的戴恩。我们认为，类似的论证表明，在 $\theta_{QED}$ 背景下，任何微观构型的电磁偶极矩 $\mu$ 会产生与 $\theta_{QED}$ 成正比的电偶极矩 $\langle d_{\rm ind} \rangle$，即 $\langle d_{\rm ind}\rangle= - \frac{\theta_{\rm QED} \cdot \alpha}{\pi} \mu$。我们还论证，由于相同的物理机制，在外部磁场 $\vec{B}_{\rm ext}$ 背景下将产生许多 $\cal{CP}$ 关联，例如 $ \langle \vec{B}_{\rm ext} \cdot\vec{E}\rangle = -\frac{\alpha\theta_{\rm QED}}{\pi}\vec{B}^2_{\rm ext}$。

英文摘要：

I highlight a few thoughts on the contribution to the dipole moments from the so-called $θ$ parameter. The dipole moments are known can be generated by $θ$. In fact, the renowned strong $\cal{CP}$ problem was formulated as a result of non-observation of the dipole moments. What is less known is that there is another parameter of the theory, the $θ_{QED}$ which becomes also a physical and observable parameter of the system when some conditions are met. This claim should be contrasted with conventional (and very naive) viewpoint that the $θ_{\rm QED}$ is unphysical and unobservable. A specific manifestation of this phenomenon is the so-called Witten effect when the magnetic monopole becomes the dyon with induced electric charge $e'=-e \frac{θ_{QED}}{2π}$. We argued that the similar arguments suggest that the electric magnetic dipole moment $μ$ of any microscopical configuration in the background of $θ_{QED}$ generates the electric dipole moment $\langle d_{\rm ind} \rangle $ proportional to $θ_{QED}$, i.e. $\langle d_{\rm ind}\rangle= - \frac{θ_{\rm QED} \cdot α}π μ$. We also argue that many $\cal{CP}$ correlations such as $ \langle \vec{B}_{\rm ext} \cdot\vec{E}\rangle = -\frac{αθ_{\rm QED}}π\vec{B}^2_{\rm ext}$ will be generated in the background of an external magnetic field $\vec{B}_{\rm ext} $ as a result of the same physics.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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