Related papers: Heavy Neutral Leptons from kaon decays in the SHiP…
This article presents a model independent search for an additional, mostly sterile, Heavy Neutral Lepton (HNL), that is capable of mixing with the Standard Model $\tau$ neutrino with a mixing strength of $|U_{\tau 4}|^{2}$, corresponding to…
Despite the undeniable success of the Standard Model of particle physics (SM), there are some phenomena that the SM can't explain. These phenomena indicate that the SM has to be modified. One of the possible ways to extend the SM is to…
We consider the dipole portal to sterile neutrinos, also called heavy neutral leptons (HNLs). The dipole interaction with the photon leads to HNL production in meson decays, as well as triggers the HNL decay into an active neutrino and a…
In the framework of the low-energy effective field theory of the Standard Model extended with heavy neutral leptons (HNLs), we calculate the production rates of HNLs from meson decays triggered by dimension-six operators. We consider both…
We study the search prospect of long-lived heavy neutral leptons (HNLs) pair produced in decays of axionlike particles (ALPs) at the proposed Super Tau-Charm Facility (STCF), focusing on the center-of-mass energy of $\sqrt{s}=3.773$ GeV.…
A search is performed for long-lived heavy neutral leptons (HNLs), produced through the decay of a $W$ boson along with a muon or electron. Two channels are explored: a leptonic channel, in which the HNL decays into two leptons and a…
The model of heavy neutral leptons (HNLs) is one of the well-motivated models beyond the standard model (BSM) from both theoretical and phenomenological point of views. It is an indispensable ingredient to explain the puzzle of tiny…
The SHiP experiment is designed to search for very weakly interacting particles beyond the Standard Model which are produced in a 400 GeV/c proton beam dump at the CERN SPS. An essential task for the experiment is to keep the Standard Model…
The discovery of non-zero neutrino masses points to the likely existence of multiple SM neutral fermions. When such states are heavy enough that they cannot be produced in oscillations, they are referred to as Heavy Neutral Leptons (HNLs).…
The smallness of neutrino masses provides a tantalizing allusion to physics beyond the standard model. Heavy neutral leptons ($N$), such as hypothetical sterile neutrinos, accommodate a way to explain this observation, through the see-saw…
We explore the feasibility of detecting heavy neutrinos by the existing facilities of neutrino experiments. A heavy neutrino in the mass range 1 MeV < M < 500 MeV is produced by pion or kaon decay, and decays to charged particles which…
Heavy Neutral Leptons (HNLs) are a popular extension of the Standard Model to explain the lightness of neutrino masses and the matter-antimatter asymmetry through leptogenesis. Future direct searches, such as fixed target setups like DUNE,…
We study the LHC discovery potential in the search for heavy neutral leptons (HNL) with a new signature: a displaced shower in the CMS muon detector, giving rise to a large cluster of hits forming a displaced shower. A new Delphes module is…
A search for neutral heavy leptons (NHLs) has been performed using an instrumented decay channel at the NuTeV (E-815) experiment at Fermilab. The decay channel was composed of helium bags interspersed with drift chambers, and was used in…
The phenomenology in the neutrino sector requires physics beyond the Standard Model. One possibility is the existence of new massive leptonic states which could be probed at the high intensity machines. The present results on heavy neutral…
We study the expected sensitivity to the mixing between sterile and tau neutrinos directly from the tau neutrino disappearance in the high-energy fixed target experiment. Here, the beam energy is large enough to produce tau neutrinos at the…
Measuring the rate at which the long-lived, neutral kaon decays into a neutral pion, neutrino, and anti-neutrino allows physicists an opportunity to test precise predictions made by the Standard Model. Differences between theoretical…
The production of heavy sterile neutrinos from $\pi^-,K^-$ decay at rest yields charged leptons with negative helicity (positive for $\pi^+,K^+$). We obtain the branching ratio for this process and argue that a Stern-Gerlach filter leads to…
The NA48/2 and NA62-$R_K$ experiments at the CERN SPS collected large samples of charged kaon decays in flight in 2003--07. The data analysis is still on-going (with over 20 publications produced so far); the recent results from these…
We study primordial nucleosynthesis abundance yields for assumed ranges of cosmological lepton numbers, sterile neutrino mass-squared differences and active-sterile vacuum mixing angles. We fix the baryon-to-photon ratio at the value…