$K_L\to\pi^0\nu\bar\nu$、$K_S\to\mu^+\mu^-$、$K_L\to\pi^0 \ell^+\ell^-$ 和 $\varepsilon^\prime/\varepsilon$ 在 NA62 新的 $K^+\to\pi^+\nu\bar\nu$ 结果后的前景
Prospects for $K_{L}\toπ^{0}ν\barν$, $K_S\toμ^+μ^-$, $K_L\toπ^0 \ell^+\ell^-$ and $\varepsilon^{\prime}/\varepsilon$ after the new $K^{+}\toπ^{+}ν\barν$ result from NA62
浏览论文内容
中文总结 AI 辅助
基于 NA62 新结果，研究 $K_L\to\pi^0\nu\bar\nu$ 等衰变的前景，通过引入新相位和右手法耦合，提升分支比并消除 $\varepsilon^{\prime}/\varepsilon$ 异常。
中文摘要 AI 辅助
最近宣布的 NA62 测量 $K^{+}\to\pi^{+}\nu\bar{\nu}$ 分支比的结果，基于 2016-2024 年的数据，完全一致于其非常精确的标准模型（SM）预测。虽然不能排除基于 2016-2026 年数据的最终结果会偏离 SM 预测，但问题在于 $K_{L}\to\pi^{0}\nu\bar{\nu}$ 衰变是否也会遭遇类似命运。该衰变目前由 KOTO 实验搜索，目前的上限大致比其非常精确的 SM 预测高两个数量级。所提出的 KOTO II 实验旨在提供 $K_{L}\to\pi^{0}\nu\bar{\nu}$ 衰变的首次发现并测量其分支比。基于之前几篇论文的研究发现，如果我们选择适当的大型新复相位和少量的新右手法 $\bar{s}d$ 耦合（除了左手法耦合外），$K_{L}\to\pi^{0}\nu\bar{\nu}$ 分支比可以比 SM 预测提高一个数量级，同时保持 $K^{+}\to\pi^{+}\nu\bar{\nu}$ 和 $\varepsilon_K$ 的 SM 类型。同时，$K_S\to\mu^+\mu^-$ 衰变（由 LHCb 研究）和 $K_L\to\pi^0\ell^+\ell^-$ 衰变（由 KOTO II 搜索）可以显著增强，而 Dual QCD 声称的 $\varepsilon^{\prime}/\varepsilon$ 比例中的异常可以被消除。我们通过一个具体的 $Z^\prime$ 情景来说明这一点。
英文摘要
The recently announced NA62 measurement of the $K^{+}\toπ^{+}ν\barν$ branching ratio, based on 2016--2024 data, is fully consistent with its very accurate Standard Model (SM) prediction. While it is not excluded that the final result based on 2016--2026 data will deviate from the SM prediction, the question arises whether a similar fate awaits the $K_{L}\toπ^{0}ν\barν$ decay. This decay is currently being searched for by the KOTO experiment, with the present upper bound roughly two orders of magnitude above its very precise SM prediction. The proposed KOTO II experiment aims to provide the first discovery of the $K_{L}\toπ^{0}ν\barν$ decay and measure its branching ratio. Building on the findings of several previous papers we demonstrate that in the presence of suitably chosen large new complex phases and of a small amount of new right-handed $\bar s d$ couplings, in addition to the left-handed ones, the $K_{L}\toπ^{0}ν\barν$ branching ratio can still be enhanced by one order of magnitude with respect to the SM prediction while keeping both $K^{+}\toπ^{+}ν\barν$ and $\varepsilon_K$ SM-like. Simultaneously the decays $K_S\toμ^+μ^-$, studied by LHCb, and $K_L\toπ^0\ell^+\ell^-$, searched for by KOTO II, can be strongly enhanced and the anomaly in the ratio $\varepsilon^{\prime}/\varepsilon$, as claimed by Dual QCD, removed. We illustrate this with an example of a specific $Z^\prime$ scenario.
