Possible explanation of not observing ultra-high energy cosmic neutrinos

TL;DR

This paper explores the hypothesis that neutrinos are tachyonic, calculating their decay widths and suggesting that such properties could explain the absence of ultra-high energy cosmic neutrinos observed by IceCube.

Contribution

It introduces a novel tachyonic neutrino decay model and derives upper mass limits based on cosmological neutrino observations, linking theoretical physics with experimental data.

Findings

Tachyonic neutrinos could decay over cosmological distances, reducing high-energy neutrino flux.

Estimated upper limits on spacelike neutrino mass are comparable to KATRIN experiment bounds.

Proposes a potential explanation for the non-observation of ultra-high energy cosmic neutrinos.

Abstract

Assuming that neutrinos are spacelike (tachyonic) fermions, we calculate width for the kinematically allowed, lepton number conserving, three-body decay $\nu_{\alpha}\rightarrow \nu_{\alpha} \; \nu_{\beta} \bar{\nu}_{\beta}$ in the Standard Model. Decays of tachyonic neutrinos over cosmological distances can lead to a reduction of the neutrino flux in the high-energy end of the spectrum. We estimate upper limits on the spacelike neutrino mass based on the PeV-energy cosmological neutrino events observed in the IceCube experiment. These limits are close to those deduced from the measurements of $m_{\nu}^2$ in the tritium-decay experiment KATRIN.