利用$K_L$衰变改进轻子味普适性测试
Improving lepton flavour universality tests with $K_L$ decays
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中文总结 AI 辅助
该研究通过全局分析稀有K介子衰变数据，结合NA62与KOTO-II的未来测量，改进轻子味普适性测试，为探测标准模型外新物理提供灵敏探针。
中文摘要 AI 辅助
稀有K介子衰变是探测标准模型（Standard Model）味结构及可能的新物理的灵敏探针。我们开展了一项全局分析，纳入了最新的实验结果与更新后的标准模型预测，包括$K^+ \to \pi^+ \nu\bar{\nu}$的最新测量结果，以及$K^+ \to \pi^+ \bar{\nu}\bar{\nu}$和$K^+ \to \tau^+ \tau^-$中的轻子味普适性可观测量。拟合结果显示，最佳拟合点接近标准模型，同时存在另一个在唯象学上仍具相关性的局域极小值。我们定义了与这两个区域相关的基准场景，并研究了NA62和KOTO-II对新物理参数空间的预期灵敏度。我们考虑了NA62对$K^+ \to \bar{\nu}\bar{\nu}$和$K^+ \to \tau^+ \tau^-$中轻子味普适性可观测量的预期测量，以及KOTO-II对$K_L \to \bar{\nu}\bar{\nu}$、$K_L \to e^+e^-$和$K_L \to \tau^+ \tau^-$的预期测量。我们发现KOTO-II在探测和区分可行的新物理场景方面具有显著潜力，而NA62则提供互补的灵敏度。
英文摘要
Rare kaon decays provide sensitive probes of the flavour structure of the Standard Model and of possible new physics. We perform a global analysis incorporating recent experimental results and updated Standard Model predictions, including the latest measurement of $K^+ \to π^+ ν\barν$ and lepton flavour universality observables in $K^+ \to π^+ \ell^+\ell^-$. The fit favours a best-fit point close to the Standard Model, while a second local minimum remains phenomenologically relevant. We define benchmark scenarios associated with these two regions and investigate the prospective sensitivity of NA62 and KOTO-II to the new physics parameter space. We consider projected measurements of $K^+ \to π^+ ν\barν$ and lepton flavour universality observables in $K^+ \to π^+ \ell^+\ell^-$ at NA62, and of $K_L \to π^0 ν\barν$, $K_L \to π^0 e^+e^-$, and $K_L \to π^0 μ^+μ^-$ at KOTO-II. We find that KOTO-II has significant potential to probe and discriminate between the viable new physics scenarios, with NA62 providing complementary sensitivity.
