2 Search Results

The NA62 experiment at CERN 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 particles, including dark photons, dark scalars, and axion-like particles, may be produced in the absorber and decay in the instrumented volume beginning approximately 80 m downstream of the dump. A search for these particles decaying in flight to hadronic final states is reported, based on an analysis of a sample of 1.4 x 10¹⁷ protons on dump collected in 2021. No evidence of a New Physics signal is observed, excluding newmore » regions of parameter spaces of multiple models.« less

A measurement of the $${K}^{+}\to {\pi}^{+}\nu \overline{\nu}$$ decay by the NA62 experiment at the CERN SPS is presented, using data collected in 2021 and 2022. This dataset was recorded, after modifications to the beamline and detectors, at a higher instantaneous beam intensity with respect to the 2016–2018 data taking. Combining NA62 data collected in 2016–2022, a measurement $$\mathcal{B} ({K}^{+}\to {\pi}^{+}\nu \overline{\nu}) = \large{(}13.0^{+3.3}_{-3.0}\large{)}$$ x $$10^{-11}$$ of is reported. With 51 signal candidates observed and an expected background of $$18^{+3}_{-2}$$ events, $$\mathcal{B} ({K}^{+}\to {\pi}^{+}\nu \overline{\nu})$$ becomes the smallest branching ratio measured with a signal significance above 5σ.