A search for heavy neutral lepton (N) production in K+→e+N decays using the data sample collected by the NA62 experiment at CERN in 2017–2018 is reported. Upper limits of the extended neutrino mixing matrix element |Ue4|2 are established at the level of 10−9 over most of the accessible heavy neutral lepton mass range 144–462 MeV/c2, with the assumption that the lifetime exceeds 50 ns. These limits improve significantly upon those of previous production and decay searches. The |Ue4|2 range favoured by Big Bang Nucleosynthesis is excluded up to a mass of about 340 MeV/c2
A search for heavy neutral lepton production in K+ decays using a data sample collected with a minim...
A search for heavy neutral lepton production in decays using a data sample collected with a minimum ...
A search for heavy neutral lepton (N) production in K+ -> mu N+ and K+ -> e(+)N decays is carr...
A search for heavy neutral lepton (N) production in K+→e+N decays using the data sample collected by...
A search for heavy neutral lepton (N) production in K+→e+N decays using the data sample collected by...
A search for heavy neutral lepton (N) production in decays using the data sample collected by the NA...
A search for heavy neutral lepton production in K+ decays using a data sample collected with a minim...
Searches for heavy neutral lepton production in K+ → e+N and K+ → μ+N decays using the data set coll...
A search for heavy neutral lepton production in K+ decays using a data sample collected with a minim...
A search for heavy neutral lepton production in K+ decays using a data sample collected with a minim...
A search for heavy neutral lepton production in decays using a data sample collected with a minimum ...
A search for heavy neutral lepton (N) production in K+ -> mu N+ and K+ -> e(+)N decays is carr...
A search for heavy neutral lepton (N) production in K+→e+N decays using the data sample collected by...
A search for heavy neutral lepton (N) production in K+→e+N decays using the data sample collected by...
A search for heavy neutral lepton (N) production in decays using the data sample collected by the NA...
A search for heavy neutral lepton production in K+ decays using a data sample collected with a minim...
Searches for heavy neutral lepton production in K+ → e+N and K+ → μ+N decays using the data set coll...
A search for heavy neutral lepton production in K+ decays using a data sample collected with a minim...
A search for heavy neutral lepton production in K+ decays using a data sample collected with a minim...
A search for heavy neutral lepton production in decays using a data sample collected with a minimum ...
A search for heavy neutral lepton (N) production in K+ -> mu N+ and K+ -> e(+)N decays is carr...