Speaker
Dr
Toshio Numao
(TRIUMF)
Description
The branching ratio of pion decays, R=B(pi-->e nu)/B(pi-->mu nu), has provided the best test of electron-muon universality in weak interactions. While the Standard Model prediction is R=(1.2353+-0.0001)x10^-4, the existing experimental results, R=(1.2265+-0.0056)x10^-4 (TRIUMF) and R=(1.2346+-0.0050)x10^-4 (PSI), are still two orders of magnitude less precise. Since this branching ratio is sensitive to the presence of pseudoscalar couplings, a wide range for new physics up to 1000 TeV can be searched for by improving the measurement by an order of magnitude.
In this talk we discuss the motivation and the status of the new experiments for the branching ratio measurement as well as related pion decays.
Primary author
Dr
Toshio Numao
(TRIUMF)
