Search results for "Heavy Neutrino"
showing 4 items of 14 documents
Search for heavy neutrinos in K + → μ + ν μ decays
2017
The NA62 experiment recorded a large sample of K+→μ+νμ decays in 2007. A peak search has been performed in the reconstructed missing mass spectrum. In the absence of a signal, limits in the range 2×10−6 to 10−5 have been set on the squared mixing matrix element |Uμ4|2 between muon and heavy neutrino states, for heavy neutrino masses in the range 300–375 MeV/ c2 . The result extends the range of masses for which upper limits have been set on the value of |Uμ4|2 in previous production search experiments.
Search for heavy neutrinos at the NA48/2 and NA62 experiments at CERN
2018
© The Authors, published by EDP Sciences. The NA48/2 experiment at CERN has collected large samples of charged kaons decaying into a pion and two muons for the search of heavy nuetrinos. In addition, its successor NA62 has set new limits on the rate of charged kaon decay into a heavy neutral lepton (HNL) and a lepton, with = e, µ, using the data collected in 2007 and 2015. New limits on heavy neutrinos from kaon decays into pions, muons and positrons are presented in this report.
Beyond the Minimal Standard Model
2011
The GSW theory is a great step forward in our understanding of electroweak interactions because it allows the well-known extremely successful theory of quantized electrodynamics and the theory of the weak CC and NC interactions to be cast into one unified, renormalizable local gauge theory. Renormalizability, in particular, is a very desirable property of the theory because it makes covariant perturbation theory a reasonable and well-defined approximation method for calculating physical quantities beyond the lowest order diagrams. Nevertheless, this model, very likely, is not the corner stone of a final theory of weak and electromagnetic interactions. It contains very many parameters which …
Search for heavy neutrinos with the T2K near detector ND280
2019
This paper reports on the search for heavy neutrinos with masses in the range 140<MN<493 MeV/c2 using the off-axis near detector ND280 of the T2K experiment. These particles can be produced from kaon decays in the standard neutrino beam and then subsequently decay in ND280. The decay modes under consideration are N→ℓ±απ∓ and N→ℓ+αℓ−β(−)ν(α,β=e,μ). A search for such events has been made using the Time Projection Chambers of ND280, where the background has been reduced to less than two events in the current dataset in all channels. No excess has been observed in the signal region. A combined Bayesian statistical approach has been applied to extract upper limits on the mixing elements of heav…