PHYSICS BEYOND THE STANDARD MODEL WITH THE NA62 EXPERIMENT AT CERN

The NA62 experiment at CERN is a high-intensity kaon decay experiment with a very broad physics program. Between 2016 and 2018, it collected the world’s largest dataset of K⁺ decays, which led to the first measurement of the branching ratio of the rare K⁺ → π⁺νν (PNN) decay, observed with a significance of 3.4σ. At the same time, several other new-physics (NP) studies are carried out. For example, the experiment is very active in the search for lepton-flavour/number-violating kaon decays, the most recent result concerning the K⁺ → µ^-νe⁺e⁺ channel. Moreover, limits were recently set on the existence of evidence of a dark (pseudo-) scalar in the PNN dataset and hidden-sector mediators are sought in the K⁺ → π⁺e⁺e⁺e^-e^- channel. In 2021, the experiment was run in beam-dump mode for the first time. This allows for new searches for exotic particles — for instance, a massive dark photon which decays into a µ⁺µ^- pair is sought.