Precision tests of electron-muon universality with pions

T. Numao, A. Aguilar-Arevalo, M. Aoki, M. Blecher, D. I. Britton, D. A. Bryman, S. Chen, J. Comfort, M. M. Ding, L. Doria, P. Gumplinger, A. Hussein, Y. Igarashi, S. H. Kettell, L. Kurchaninov, L. Littenberg, C. Malbrunot, A. Sher, T. Sullivan, V. VavilovY. Yoshida, K. Yamada

Research output: Contribution to journalArticlepeer-review


The TRIUMF PIENU experiment aims to measure the branching ratio of pion decays, Re/μ = Γ(π → eν(γ))/Γ(π → μν(γ)), at a precision level of < 0.1%, confronting the Standard Model (SM) prediction of RSM e/μ = 1.2353(1) × 10-4. At that level, new physics beyond the SM involving mass scales up to 1000TeV may be heralded by an observed deviation from the precise SM expectation. Also, evidence of massive neutrinos in the π+ → e+ν decay spectrum has been sought with the background from π+ → μ+ → e+ decay chain highly suppressed. Upper limits (90% C.L.) on the neutrino mixing matrix element |Uei|2 in the mass region 65-130 MeV/c2 have been set at a 10-8 level.

Original languageEnglish (US)
Pages (from-to)63-67
Number of pages5
JournalNuovo Cimento della Societa Italiana di Fisica C
Issue number4
StatePublished - 2012

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Physics and Astronomy (miscellaneous)


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