Initial Results from the PIENU experiment

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

Research output: Contribution to journalConference article


The pion branching ratio, Rπ = γ(π+→e+ve+→e+veϒ) γ(π+→μ+, vμ+→μ+vμϒ) provides a sensitive test of lepton universality and constraints on many new physics scenarios. The theoretical uncertainty on the Standard Model prediction of Rπ is 0.02%, a factor of twenty smaller than the experimental uncertainty. The analysis of a subset of data taken by the PIENU experiment will be presented. The result, Rπ = (1.2344±0.0023(stat) ±0.0019(syst)) 10-4[1], is consistent with the Standard Model prediction and represents a 0.1% constraint on lepton non-universality.

Original languageEnglish
JournalProceedings of Science
VolumePart F128555
Publication statusPublished - 2016
Event13th International Conference on Heavy Quarks and Leptons, HQL 2016 - Blacksburg, United States
Duration: May 22 2016May 27 2016

ASJC Scopus subject areas

  • General

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    Sullivan, T., Aguilar-Arevalo, A., Aoki, M., Blecher, M., Britton, D. I., Bryman, D. A., Vom Bruch, D., Chen, S., Comfort, J., Cuen-Rochin, S., Doria, L., Gumplinger, P., Hussein, A., Igarashi, Y., Ito, S., Kettell, S. H., Kurchaninov, L., Littenberg, L. S., Malbrunot, C., ... Vavilov, D. (2016). Initial Results from the PIENU experiment. Proceedings of Science, Part F128555.