Recent Results from NA62 in Kaon and Dump Mode

Abstract

NA62 is a fixed-target kaon experiment at the CERN SPS. The recent measurement of the ultra-rare decay $K^+\to\pi^+\nu\bar\nu$, based on data collected between 2016 and 2024 is reported. The measurement is compatible with previous measurements and the Standard Model. The experiment can also be operated in an alternative beam-dump mode. From this mode, a search for new-physics particles with masses in the range of 150 to 2000~MeV, based on data collected in dedicated runs between 2021 and 2024 is reported. The search focuses on their decays to $h^\pm\ell^\mp$, where $h^\pm\in(\pi^\pm,\pi^\pm\pi^0,\pi^\pm2\pi^0,K^\pm)$, and $\ell\in(e,\mu)$, which are expected in heavy neutral lepton scenarios. No event was observed across all considered signal channels, and upper limits were set on the coupling of such particles to the Standard Model.