arXiv 1712.061472017-12-17hep-phhep-exhep-lat

$K^0\toππ$中的直接CP破坏：标准模型状态

Direct CP violation in $K^0\toππ$: Standard Model Status

Hector Gisbert, Antonio Pich

备注：: 45 pages, 4 figures
DOI：: 10.1088/1361-6633/aac18e

摘要：

1988年，NA 31实验首次给出了$K^0\toππ$衰变振幅中直接CP破坏的证据。后来，用来自NA31、E731、NA48和KTeV实验的完整数据样本建立了具有$7.2\,σ$统计显著性的清晰信号，证实CP破坏与$ΔS=1$夸克跃迁有关，正如标准模型所预测的那样。然而，多年来，对测量比率$\varepsilon'/\varepsilon$的理论预测一直是一个具有强烈争议的主题。虽然在2001年已经阐明了基本的物理学，但最近发布的改进的晶格数据再次引发了理论辩论。我们回顾了目前的状况，详细讨论了不同的成分，进入这个观察到的计算和原因，似乎矛盾的预测，在过去获得的几个团体。本文介绍了标准模型预测的最新情况，并分析了今后改进的前景。考虑到所有已知的短距离和长距离的贡献，一个得到$\mbox{Re}\left(\varepsilon'/\varepsilon\right) = (15 \pm 7)\cdot 10^{-4}$，与实验测量的良好协议。

英文摘要：

In 1988 the NA31 experiment presented the first evidence of direct CP violation in the $K^0\toππ$ decay amplitudes. A clear signal with a $7.2\,σ$ statistical significance was later established with the full data samples from the NA31, E731, NA48 and KTeV experiments, confirming that CP violation is associated with a $ΔS=1$ quark transition, as predicted by the Standard Model. However, the theoretical prediction for the measured ratio $\varepsilon'/\varepsilon$ has been a subject of strong controversy along the years. Although the underlying physics was already clarified in 2001, the recent release of improved lattice data has revived again the theoretical debate. We review the current status, discussing in detail the different ingredients that enter into the calculation of this observable and the reasons why seemingly contradictory predictions were obtained in the past by several groups. An update of the Standard Model prediction is presented and the prospects for future improvements are analysed. Taking into account all known short-distance and long-distance contributions, one obtains $\mbox{Re}\left(\varepsilon'/\varepsilon\right) = (15 \pm 7)\cdot 10^{-4}$, in good agreement with the experimental measurement.

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。

摘要：

英文摘要：

相关论文