New measurement of the $K^{+}\rightarrow\pi^{+}\nu\bar{\nu}$ decay at NA62

by Joel Christopher Swallow (Istituto Nazionale di Fisica Nucleare)

Wednesday Mar 25, 2026, 2:30 PM → 4:00 PM Europe/Rome

Aula Touschek (Laboratori Nazionali di Frascati)

The $K^{+}\rightarrow\pi^{+}\nu\bar{\nu}$ decay is a golden mode for flavour physics. Using data collected in 2016–2022 NA62 announced the first observation of this decay with a signal significance above 5 sigma and the measurement $\mathcal{B}(K^{+}\rightarrow\pi^{+}\nu\bar{\nu})=(13.0^{+3.3}_{-3.0})\times10^{-11}$. New results from the analysis of the 2023–2024 dataset are presented. This dataset doubles the effective sample size. Reconstruction and selection algorithms have been improved, boosting sensitivity and reducing the background contamination.  An updated measurement of the $K^{+}\rightarrow\pi^{+}\nu\bar{\nu}$ branching ratio is presented and prospects for the full 2016–2026 dataset are discussed. A summary of other recent NA62 results will also be presented.

Locandina_SWALLOW.docx