arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1608.07484nucl-thhep-phnucl-ex
收藏

强子弱荷与宇称破坏前向康普顿散射

Hadronic weak charges and parity-violating forward Compton scattering

Mikhail Gorchtein, Hubert Spiesberger

备注：
Few references added; small changes in the text
发表信息：
Phys. Rev. C 94, 055502 (2016)
阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

在低动量转移时，宇称破坏的电子-核子弹性散射允许人们接近核子的弱电荷，即$Z$-玻色子与核子的矢量耦合。在标准模型和树水平下，质子的弱电荷与弱混合角有关，并且偶然被抑制，$Q_W^{p,\,{\rm tree}}=1-4\sin^2θ_W\approx0.07$。现代实验旨在以$\sim1\%$精度提取$Q_W^p$。类似地，原子中的宇称不守恒允许访问原子核的弱电荷。我们考虑一类新的辐射修正，在强子/核系统的宇称破坏的两个光子的交换。这些校正可能会影响以相关精度水平从实验数据中提取$\sin^2θ_W$，因为它们受到类似于其他违反宇称的辐射校正的长程相互作用的影响，例如，$γZ$-交换，最近得到了很多关注。我们发现，这种新的校正的意义增加的宇称违反电子散射的束能量，但宇称违反前向康普顿振幅的一般性质保护的形式定义的弱电荷作为限制在零动量转移和零能量。我们还讨论了即将到来的实验的新的校正的相关性。

英文摘要：

Parity-violating elastic electron-nucleon scattering at low momentum transfer allows one to access the nucleon's weak charge, the vector coupling of the $Z$-boson to the nucleon. In the Standard Model and at tree level, the weak charge of the proton is related to the weak mixing angle and accidentally suppressed, $Q_W^{p,\,{\rm tree}}=1-4\sin^2θ_W\approx0.07$. Modern experiments aim at extracting $Q_W^p$ at $\sim1\%$ accuracy. Similarly, parity non-conservation in atoms allows to access the weak charge of atomic nuclei. We consider a novel class of radiative corrections, an exchange of two photons with parity violation in the hadronic/nuclear system. These corrections may affect the extraction of $\sin^2θ_W$ from the experimental data at the relevant level of precision because they are affected by long-range interactions similar to other parity-violating radiative corrections, such as, e.g., the $γZ$-exchange, which has obtained much attention recently. We show that the significance of this new correction increases with the beam energy in parity-violating electron scattering, but the general properties of the parity-violating forward Compton amplitude protect the formal definition of the weak charge as a limit at zero-momentum transfer and zero-energy. We also discuss the relevance of the new correction for upcoming experiments.

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。

↑