First Observation of D+ → ημ+νμ and Measurement of Its Decay Dynamics
First Observation of D+ → ημ+νμ and Measurement of Its Decay Dynamics
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D 的首次观测及其衰变动力学的测量
DOI：
10.1103/physrevlett.124.231801
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发表时间：
2020
影响因子：
8.6
通讯作者：
BESIII Collaboration
中科院分区：
文献类型：
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作者：
BESIII Collaboration
通过对质心能量为3.773 GeV的积分光度数据的分析，我们首次测得衰变的绝对分支分数为BD+→ημ+νμ=(10.4±1.0stat±0.5syst)×10~(-4)。利用的世界平均值确定两个分支分数的比值为bd+→ημ+νμ/bd+→ηe+νe=0.91±0.13(STAT+SYST)，这与轻子味普适性在不确定度范围内的理论预期一致。通过研究五个四动量转移区间内的微分衰减率，我们得到了强子形式因子与Cabibbo-Kobayashi-Maskawa矩阵元的乘积为f+η(0)|vcd|=0.087±0.008stat±0.002syst。从标准模型中的全局拟合中提取输入，我们确定。另一方面，利用理论计算的值，我们得到|Vcd|=0.242±0.022stat±0.006syst±0.033。
By analyzing a data sample corresponding to an integrated luminosity ofcollected 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 thedecay to be BD+→ημ+νμ=(10.4±1.0stat±0.5syst)×10-4. Using the world averaged value of, the ratio of the two branching fractions is determined to be BD+→ημ+νμ/BD+→ηe+νe=0.91±0.13(stat+syst), which agrees with the theoretical expectation of lepton flavor universality within uncertainty. By studying the differential decay rates in five four-momentum transfer intervals, we obtain the product of the hadronic form factorand theCabibbo-Kobayashi-Maskawa matrix elementto be f+η(0)|Vcd|=0.087±0.008stat±0.002syst. Taking the input offrom the global fit in the standard model, we determine. On the other hand, using the value ofcalculated in theory, we find |Vcd|=0.242±0.022stat±0.006syst±0.033theory.