PIONEER: A next-generation rare pion decay experiment

by David Hertzog (University of Washington)

Thursday 2 Oct 2025, 15:00 → 16:00 Europe/Rome

Sala G. Galilei (131) (INFN - Pisa)

Abstract: 

The fundamental principle of Flavor Universality is a centerpiece 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 the rare pion decay measurements up to 15-fold over the current ones and probe the Standard Model at energy scales beyond the reach of colliders. Our experiment design benefits from past-generation experiments and employs emergent technologies in tracking and calorimetry. In this talk, I will discuss the physics case of the experiment, review its conceptual design and present the ongoing R&D effort toward building the detector for the first phase of the project. I will also describe the additional physics goals, which include exotic searches and, in a slightly reconfigured setup, a measurement of pion beta decay to determine Vud in a theoretically clean manner.