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 …

A search for heavy neutral lepton production in K+ decays using a data sample collected
with a minimum bias trigger by the NA62 experiment at CERN in 2015 is reported. Upper …

The NA62 experiment at CERN reports searches for K+→ μ+ N and K+→ μ+ ν X decays,
where N and X are massive invisible particles, using the 2016–2018 data set. The N particle …

We investigate mixing of neutrinos in the νMSM (neutrino Minimal Standard Model), which is
the MSM extended by three right-handed neutrinos. Especially, we study elements of the …

The NA62 experiment at CERN reports a search for the lepton number violating decays
K+→ π− e+ e+ and K+→ π− μ+ μ+ using a data sample collected in 2017. No signals are …

Evidence of a heavy neutrino, ν H, in the K+→ μ+ ν H decays was sought using the E949
experimental data with an exposure of 1.70× 1 0 12 stopped kaons. With the major …

Evidence of massive neutrinos in the π+→ e+ ν decay spectrum was sought with the
background π+→ μ+→ e+ decay chain highly suppressed. Upper limits (90% CL) on the …

Heavy neutral leptons (N) below the kaon mass are severely constrained by cosmology and
lab-based searches for their decays in flight. If N interacts via an additional force, N→ ν e+ e …

We study experimental and cosmological constraints on the extension of the Standard
Model by three right handed neutrinos with masses between those of the pion and W boson …

We report on a search for the first generation heavy neutrino that is an isosinglet under the
standard SU (2) L gauge group. The data collected with the L3 detector at center-of-mass …