Are Muons Just Heavy Electrons? Precision Tests of the Standard Model with PIONEER.

by Quentin Buat (University of Washington (US))

Friday 4 Dec 2026, 11:00 → 12:00 Europe/Zurich

40/S2-A01 - Salle Anderson (CERN)

The electron was the first elementary particle ever discovered, and it plays a starring role across physics, from electricity to chemistry. Its heavier cousins, the muon and the tau, look at first glance like simple copies in a different flavor, governed by the same interaction rules — a principle known as Lepton Flavor Universality and a cornerstone of the Standard Model of Particle Physics. PIONEER is a new experiment set to challenge this principle by studying the rarest decays of the charged pion. With this new apparatus, we aim to improve branching fraction measurements up to 15-fold over the current ones and probe the Standard Model at energy scales beyond the reach of any collider. Our experiment design benefits from earlier experiments while pushing emergent technologies in particle tracking and calorimetry. In this talk, I will present the physics case for PIONEER, its conceptual design and the ongoing R&D effort toward building the detector and the beamline for the experiment’s first phase.

 

Coffee will be served at 10:30