MBI seminar: Searching for new physics with PSI’s low energy pions: the PIONEER experiment

by Dr Chloé Malbrunot (TRIUMF Vancouver, Canada / UBC Vancouver, Canada / McGill University, Montreal, Canada)

Friday 13 Mar 2026, 13:00 → 14:00 Europe/Vienna

Besprechungsraum #4”, 4th floor of PSK (Marietta Blau Institute for Particle Physics, Dominikanerbastei 16 [PSK], 1010 Vienna)

The PIENU experiment at TRIUMF has provided, to date, the most precise experimental determination of R(π->e/µ) the ratio of pions decaying to positrons relative to muons. While more than an order of magnitude less precise than the Standard Model (SM) calculation, the PIENU result is the most precise test of the universality of charged leptons interaction, a key principle of the Standard Model (SM), constrains a large range of new physics scenario, and allows dedicated searches for exotics such as sterile neutrinos. I’ll go over a short overview of R(π->e/µ) measurements and introduce the next generation precision pion decay experiment in the making: PIONEER.

 

This newly proposed experiment which was approved with high priority at the Paul Scherrer Institute aims at pushing the boundaries of precision on  R(π->e/µ) and expanding the physics reach by improving on the measurement of the very rare pion beta decay π+ → π0 e+ν. This will provide a new and competitive input to the determination of |Vud|, an element of the Cabibbo- Kobayashi-Maskawa (CKM) quark-mixing matrix.