First NA62 search for long-lived new physics particle hadronic decays

The NA62 experiment at CERN, designed to measure the highly-suppressed decay $K^{+}\to\pi^{+}\nu\bar{\nu}$, has the capability to collect data in a beam-dump mode, where 400 GeV protons are dumped on an absorber. In this configuration, New Physics (NP) particles, including dark photons, dark scalars and axion-like particles, may be produced and reach a decay volume beginning 80 m downstream of the absorber. A search for NP particles decaying in flight to hadronic final states is reported, based on a blind analysis of a sample of $1.4\times10^{17}$ protons on dump collected in 2021.