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arXiv · 1506.05845

Improved measurement of the $\pi \rightarrow \mbox{e} \nu$ branching ratio

A. Aguilar-Arevalo·M. Aoki·M. Blecher·D. I. Britton·D. A. Bryman·D. vom Bruch·S. Chen·J. Comfort·M. Ding·L. Doria·S. Cuen-Rochin·P. Gumplinger·A. Hussein·Y. Igarashi·S. Ito·S. H. Kettell·L. Kurchaninov·L. S. Littenberg·C. Malbrunot·R. E. Mischke·T. Numao·D. Protopopescu·A. Sher·T. Sullivan·D. Vavilov·K. Yamada
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Abstract

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

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A. Aguilar-Arevalo, M. Aoki, M. Blecher, D. I. Britton, D. A. Bryman, D. vom Bruch, S. Chen, J. Comfort, M. Ding, L. Doria, S. Cuen-Rochin, P. Gumplinger, A. Hussein, Y. Igarashi, S. Ito, S. H. Kettell, L. Kurchaninov, L. S. Littenberg, C. Malbrunot, R. E. Mischke, T. Numao, D. Protopopescu, A. Sher, T. Sullivan, D. Vavilov, K. Yamada. 2015-06-18. Improved measurement of the $\pi \rightarrow \mbox{e} \nu$ branching ratio. https://doi.org/10.1103/physrevlett.115.071801

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