arXiv 2502.201452025-02hep-phhep-ex

对$b\to s\ell^+\ell^-$衰变中lepton flavor universal和non-universal New Physics的约束：SMEFT的全局调查

Constraints on lepton flavor universal and non-universal New Physics in $b\, \to\, s\, \ell^+ \ell^-$ decays: a global SMEFT survey

Indian Association for the Cultivation of Science（印度科学培养协会）；Physical Research Laboratory（物理研究实验室）

Md Isha Ali, Utpal Chattopadhyay, Dilip Kumar Ghosh, N Rajeev

备注：: 31 pages, 10 figures, 24 tables , matches with the published version

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AI总结：

本文通过SMEFT框架对$b\to s\ell^+\ell^-$衰变数据进行全局分析，探讨lepton flavor universal和non-universal新物理的约束。

摘要：

$B$介子的味改变中性电流半轻子衰变为间接探测超出标准模型（SM）的新物理（NP）提供了绝佳平台。最近对lepton flavor universality（LFU）比值如$R_K$、$R_{K^*}$和$R_ϕ$的测量与SM预测一致，从而减少了早期LFU违反的提示。然而，在个别分支比中仍然存在显著矛盾——例如$\mathcal{B}(B^+\to K^+ μ^+ μ^-)$和$\mathcal{B}(B^+\to K^+ e^+ e^-)$在低$q^2$区域（[1.1,6] GeV$^2$）偏离程度在4σ-5σ水平。同样，$B\to K^{*} μ^+ μ^-$中的角可观测值$P'_5$显示3.3σ偏离，而$\mathcal{B}(B_s\to ϕμ^+ μ^-)$偏离SM的程度为3.6σ。尽管这些矛盾可能在原则上源于低估的hadronic效应，但也可能表明存在NP贡献。在本工作中，我们基于维度6 SMEFT操作符框架对最新的$b\to s\ell^+\ell^-$数据进行了全局拟合。我们的分析系统地纳入了hadronic不确定性的形式因子、非可因子化修正和输入参数，从而提供了NP解释的平衡评估。我们允许NP贡献不仅出现在$b\to s μ^+ μ^-$转变中，也出现在$b\to s e^+ e^-$通道中，从而测试了lepton flavor universal（LFU）和lepton flavor universality违反（LFUV）NP场景。这些可能性的相互作用在分支比、角可观测值和$Δ$-可观测值中产生独特的特征，提供了当前味异常的全面视图。

英文摘要：

The flavor-changing neutral current semileptonic decays of $B$ mesons provide an excellent platform for indirectly probing New Physics (NP) beyond the Standard Model (SM). Recent measurements of lepton flavor universality (LFU) ratios such as $R_K$, $R_{K^*}$, and $R_ϕ$ are consistent with SM predictions, thereby reducing earlier hints of LFU violation. Nevertheless, notable tensions persist in individual branching fractions -- for instance $\mathcal{B}(B^+ \to K^+ μ^+ μ^-)$ and $\mathcal{B}(B^+ \to K^+ e^+ e^-)$, which deviate at the $4σ$--$5σ$ level in the low-$q^2$ region ($[1.1,6]$ GeV$^2$). Similarly, the angular observable $P'_5$ in $B \to K^{*} μ^+ μ^-$ shows a $3.3σ$ deviation, while $\mathcal{B}(B_s \to ϕμ^+ μ^-)$ departs from the SM by $3.6σ$. Although such discrepancies could in principle originate from underestimated hadronic effects, they may also indicate possible NP contributions. In this work, we perform a global fit to the latest $b \to s \ell^+ \ell^-$ data within the framework of dimension-6 SMEFT operators. Our analysis systematically incorporates hadronic uncertainties from form factors, non-factorizable corrections, and input parameters, thereby providing a balanced assessment of the NP interpretation. We allow for NP contributions not only in $b \to s μ^+ μ^-$ transitions but also in $b \to s e^+ e^-$ channels, thus testing both lepton flavor universal (LFU) and lepton flavor universality violating (LFUV) NP scenarios. The interplay between these possibilities yields distinctive signatures in branching fractions, angular observables, and $Δ$-observables, offering a comprehensive view of the current flavor anomalies.

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