Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de Mexico, Distrito Federal 04510 México.
Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
Phys Rev Lett. 2015 Aug 14;115(7):071801. doi: 10.1103/PhysRevLett.115.071801. Epub 2015 Aug 13.
A new measurement of the branching ratio R_{e/μ}=Γ(π^{+}→e^{+}ν+π^{+}→e^{+}νγ)/Γ(π^{+}→μ^{+}ν+π^{+}→μ^{+}νγ) resulted in R_{e/μ}^{exp}=[1.2344±0.0023(stat)±0.0019(syst)]×10^{-4}. This is in agreement with the standard model prediction and improves the test of electron-muon universality to the level of 0.1%.
一个新的分支比测量 R_{e/μ}=Γ(π^{+}→e^{+}ν+π^{+}→e^{+}νγ)/Γ(π^{+}→μ^{+}ν+π^{+}→μ^{+}νγ) 得出的结果为 R_{e/μ}^{exp}=[1.2344±0.0023(stat)±0.0019(syst)]×10^{-4}。这与标准模型的预测相符，并将电子-μ子普遍性的检验提高到了 0.1%的水平。
