Latest Results and Precision Measurements from the NA62 Experiment

The NA62 experiment at CERN collected the world’s largest dataset of charged kaon decays in 2016–2018, leading to the first measurement of the branching ratio of the ultra-rare $$K^{+}\rightarrow\pi^{+}\nu\bar{\nu}$$ decay, based on 20 candidates, and presented in 2021. In this talk the NA62 experiment reports new results from analyses of $$K^{+}\rightarrow\pi^{+}\mu^{+}\mu^{-}$$ and $$K^{+}\rightarrow\pi^{+}\gamma\gamma$$ decays, using a data sample recorded in 2017–2018. The $$K^{+}\rightarrow\pi^{+}\mu^{+}\mu^{-}$$ —sample comprises about 27k signal events with negligible background contamination, and the analysis results presented include the most precise determination of the branching ratio and the form factor. The $$K^{+}\rightarrow\pi^{+}\gamma\gamma$$ sample contains about 4k signal events with 10 $$\%$$ background contamination, and the analysis improves the precision of the branching ratio measurement by a factor of 3 with respect to the previous measurements. The NA62 experiment can also be run as a ‘‘beam-dump experiment’’ by removing the kaon production target and moving the upstream collimators into a ‘‘closed’’ position. More than $$10^{17}$$ protons on target have been collected in this way during a week-long data-taking campaign. We report on new results from analysis of this data, with a particular emphasis on Dark Photon and Axion-like particle Models.