Searches for lepton number violating $K^{+}$ decays

NA62 collaboration

The NA62 experiment at CERN reports a search for the lepton number violating decays $K^{+}\to {\pi }^{-}{e}^{+}{e}^{+}$ and $K^{+}\to {\pi }^{-}{\mu }^{+}{\mu }^{+}$ using a data sample collected in 2017. No signals are ob…