Speaker
Description
The NA62 experiment at CERN is designed to measure the highly suppressed decay $K^+\to \pi^+\nu\bar\nu$. It also has the capability to collect data in a beam-dump mode. In this configuration, $400\,\mathrm{GeV}$ protons are dumped on an absorber and New Physics (NP) particles may be produced and reach a decay volume beginning $80\,\mathrm{m}$ downstream of the absorber. A total of $6\times10^{17}$ protons on target were collected in “beam-dump” mode by NA62 in dedicated runs in 2021–2024. We present early insights from the analysis of this data, in the search for long-lived NP particles decaying in flight to semi-leptonic final states. Such a search allows probing Heavy Neutral Lepton extensions to the Standard Model. In the targeted parameter space of such NP models, the observed baryon asymmetry of the universe and small neutrino masses could be explained simultaneously.