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 journalArticlepeer-review


The pion branching ratio, (Formula Presented.), 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
Article number3
JournalHyperfine Interactions
Issue number1
Publication statusPublished - Nov 1 2017


  • Electroweak physics
  • Lepton Universality
  • Pion decay
  • Precision measurements

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Nuclear and High Energy Physics
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry


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