Improved measurement of the $��\rightarrow \mbox{e} ��$ branching ratio
説明
A new measurement of the branching ratio, $R_{e/��} =��(��^+ \rightarrow \mbox{e}^+ ��+ ��^+ \rightarrow \mbox{e}^+ ����)/ ��(��^+ \rightarrow ��^+ ��+ ��^+ \rightarrow ��^+ ����)$, resulted in $R_{e/��}^{exp} = (1.2344 \pm 0.0023 (stat) \pm 0.0019 (syst)) \times 10^{-4}$. This is in agreement with the standard model prediction and improves the test of electron-muon universality to the level of 0.1 %.
5 pages, 4 figures