Searches for lepton number violating K+ → π−e+e+ and K+ → π−π0e+e+ decays have been performed using the complete dataset collected by the NA62 experiment at CERN in 2016–2018. Upper limits of 5.3 × 10−11 and 8.5 × 10−10 are obtained on the decay branching fractions at 90% confidence level. The former result improves by a factor of four over the previous best limit, while the latter result represents the first limit on the K+ → π−π0e+e+ decay rate.
|Journal||Physics Letters B|
|Publication status||Published - 10 Jul 2022|