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.
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Physics and Astronomy (miscellaneous)