论文标题
首先观察$ d^+\至ημ^+ν_μ$及其衰减动力学的测量
First Observation of $D^+\to ημ^+ν_μ$ and Measurement of its Decay Dynamics
论文作者
论文摘要
通过分析与BESIII探测器以3.773 GEV收集的$ 2.93〜 \ MATHRM {fb}^{ - 1} $的集成发光度相对应的数据样本，我们首次衡量了$ d^+\至ημ^_ $ nc $ nc $ nc $ nc $ nc $ nc $ nc $ nc $ nc $ nc $ n c $ n c $ n c $ n c $ dead c $ dep $ dead c $ dep $ dead c $ dep $ dead c $ ne c $ n $ dead c $ n $ b} _ {d^+\ toημ^+ν_μ} =（10.4 \ pm1.0 _ {\ rm stat} \ pm0.5 _ {\ rm syst}）\ times 10^{ - 4} $。使用$ {\ Mathcal B} _ {d^+\至ηe^+ne^+ν_e} $的世界平均值，确定两个分支分数的比率为$ {\ Mathcal B} _ {d^+\ toημ^+nμ^+ν_μ}/{ ηe^+ν_e} = 0.91 \ pm0.13 $，它与不确定性内的Lepton风味普遍性的理论期望一致。在这里，不确定性是统计和系统不确定性正交的总和。通过以五个四四摩托姆传输间隔研究差衰变率，我们获得了hadronic form $ f^η_ {+}（0）$和$ c \ to d $ cabibbo-kobayashi-maskawa maskawa matrix matrix matrix $ | v_ | v_ v_ {cd} | $ be be as Be as Be as Be be d $ f^η_ {+}（0）$ $ f _ {+}^η（0）| v_ {cd} | = 0.087 \ pm0.008 _ {\ rm stat} \ pm0.002 _ {\ rm syst} $。从标准模型中的全局拟合中获取$ | v_ {cd} | $的输入，我们确定$ f _ {+}^η（0）= 0.39 \ pm0.04 _ {\ rm Stat} \ pm0.01 _ {\ rm syst} $。另一方面，使用理论上计算的$ f _+^η（0）$的值，我们发现$ | v_ {cd} | = 0.242 \ pm0.022 _ {\ rm Stat} \ pm0.006 _ {\ rm syst} \ rm syst} \ pm0.033 _ {\ rm syst}
By analyzing a data sample corresponding to an integrated luminosity of $2.93~\mathrm{fb}^{-1}$ collected at a center-of-mass energy of 3.773 GeV with the BESIII detector, we measure for the first time the absolute branching fraction of the $D^+\to ημ^+ν_μ$ decay to be ${\mathcal B}_{D^+\to ημ^+ν_μ}=(10.4\pm1.0_{\rm stat}\pm0.5_{\rm syst})\times 10^{-4}$. Using the world averaged value of ${\mathcal B}_{D^+\to ηe^+ν_e}$, the ratio of the two branching fractions is determined to be ${\mathcal B}_{D^+\to ημ^+ν_μ}/{\mathcal B}_{D^+\to ηe^+ν_e}=0.91\pm0.13$, which agrees with the theoretical expectation of lepton flavor universality within uncertainty. Here, the uncertainty is the sum in quadrature of the statistical and systematic uncertainties. By studying the differential decay rates in five four-momentum transfer intervals, we obtain the product of the hadronic form factor $f^η_{+}(0)$ and the $c\to d$ Cabibbo-Kobayashi-Maskawa matrix element $|V_{cd}|$ to be $f_{+}^η(0)|V_{cd}|=0.087\pm0.008_{\rm stat}\pm0.002_{\rm syst}$. Taking the input of $|V_{cd}|$ from the global fit in the standard model, we determine $f_{+}^η(0)=0.39\pm0.04_{\rm stat}\pm0.01_{\rm syst}$. On the other hand, using the value of $f_+^η(0)$ calculated in theory, we find $|V_{cd}|=0.242\pm0.022_{\rm stat}\pm0.006_{\rm syst}\pm0.033_{\rm theory}$.
