http://arxiv.org/abs/2211.16520
Neutrinos can be pseudo-Dirac in Nature – they can be Majorana fermions while behaving effectively as Dirac fermions. Such scenarios predict active-sterile neutrino oscillation driven by a tiny mass-squared difference $(\delta m^2)$, which is an outcome of soft-lepton number violation. Oscillations due to tiny $\delta m^2$ can take place only over astrophysical baselines and hence are not accessible in terrestrial neutrino oscillation experiments. This implies that high-energy neutrinos coming from large distances can naturally be used to test this scenario. We use the recent observation of high-energy neutrinos from the active galactic nuclei NGC 1068 by the IceCube collaboration to constrain $\delta m^2 \leq 10^{-18}{\rm eV}^2$ at more than $90\%$ confidence level – one of the strongest limits to date on the values of $\delta m^2$.
T. Rink and M. Sen
Thu, 1 Dec 22
73/85
Comments: 5 pages, 3 figures, comments welcome
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