Precision SM tests with rare kaon decays: latests measurement of the $K^+ \rightarrow \pi^+ \nu \bar{\nu}$ decay with the NA62 experiment

by Radoslav Marchevski (École Polytechnique Fédérale de Lausanne (EPFL)), Xiafei Chang (EPFL - Ecole Polytechnique Federale Lausanne (CH))

Monday 23 Mar 2026, 11:00 → 12:00 Europe/Zurich

BSP 626 (EPFL)

Abstract: The $K^+ \rightarrow \pi^+ \nu \bar{\nu}$ decay is a golden mode for flavour physics. Its branching ratio is predicted with high precision by the Standard Model to be less than $\mathcal{O}(10^{-10})$. This decay mode is highly sensitive to indirect effects of new physics up to the highest mass scales. The NA62 experiment at the CERN SPS is designed to study the $K^+ \rightarrow \pi^+ \nu \bar{\nu}$ decay, and provided the world’s most precise investigation of this decay using 2016-22 data. Building on this success the first results from a significantly improved analysis and background rejection techniques, taken in 2023-24, are presented, as well as the combination with the 2016-22 results.

23-03-26-Kaons-EPFL.pdf

seminar_lphe_032026-2.pdf