Paucity of downward UHE neutrino tracks in IceCube versus unexpected huge KM3-230213A event: solving the puzzles?

TL;DR

This work examines the puzzling KM3-230213A event reported by ARCA, highlighting its exceptionally high energy and a downward-horizontal geometry that clashes with IceCube and AUGER expectations. It argues that the floating, current-affected deep-sea ARCA array could misreconstruct arrival directions, offering a plausible atmospheric-muon–driven explanation for the event. The paper also discusses historical neutrino milestones and explores speculative models (e.g., Z-boson resonance and Z-burst) that could connect ultra-high-energy neutrinos to distant UHECR sources if such events were confirmed. Overall, it emphasizes detector geometry and environmental effects as critical factors in interpreting extreme neutrino signals and inviting broader consideration of tau-neutrino astronomy under certain conditions.

Abstract

Recently the ARCA array detector published the down-ward-horizontal event: the KM3-230213A. It appeared as the most energetic neutrino ever observed: about 200 PeV (2 10^17 eV) up to EeV (10^18 eV) energy. This huge value, is puzzling. It is not statistically consistent with several upper bound derived by two greater and longer life detectors: by IceCube and in particular by AUGER array. Asymmetry in recent IceCube neutrino alert tracks upward and downward at same horizontal angles as ARCA one, suggest that they are mostly polluted atmospheric muon bundles. This paucity also disfavor the skimming neutrino interpretation by ARCA. We suggest that the array floating and bending in the deep sea may lead, sometime, to a misleading geometry that is pointing to a wrong arrival angle direction: a much less horizontal muon (neutrino) track respect to a much real one, more inclined and vertical, due to atmospheric muon bundle or charmed single event. Contrary to present argument, if such a rare event would be soon rediscovered in data or re-observed, it would open the road to a new guaranteed Tau neutrino Astronomy. At EeV energy such upward tau air-showers should shine AUGER telescopes or blaze future satellite in Space. A previous model in astrophysics considered energetic neutrino E>>100 EeV, neutrino scattering, onto cosmic, relic, light mass ones. Their ultra-relativistic Z boson resonance formation and its decay in flight would produce hadron UHECR relics around tens-hundred EeV energy. Explaining how sources located at far distances, above the usual GZK hundred Mpc, cut off ones, may shine and cluster in AUGER or TA data.

Figures (6)

• Figure 1: The ICECUBE alert tracks recorded in last years in celestial coordinate- The up-side of each figure point to the North of the Sky. Consequently most event in South Pole array are coming from the North ( up-going) , while much less are reaching from the South (down-going tracks). The figure above, based on ICE-Cat1 catalog, refer to the late 2024 data abbasi2024icecat. The figure below is based on the up dated recent but preliminary ICE-Cat2 catalog of events, shown in 2025 zegarelli2025icecat The two figures differ by a minor angular definition and by 25 additional events in the 2025 ICECat2 ; zegarelli2025icecat
• Figure 2: The asymmetry among the $+/- 9^o$ event tracks. The paucity of downward tracks imply that the atmospheric noise is greatly polluting most of these horizontal-downward events, at similar arrival angle as the ARCA Km3 event, KM3-230213A.
• Figure 3: The asymmetry among the up and down ward event tracks. The paucity of downward tracks,( binimial probability $P$ to occur by chance is about $P= 3.3 \cdot 10^{-9}$, imply that the atmospheric noise and its filtering is excluding most down-ward tracks as polluted ones.
• Figure 4: An exaggerated geometry showing a downward-inclined charmed muon track (yellow large dashed line) . The alternative neutrino track (red smaller dashed line) following ARCA event interpretation km3net2025observation. The horizontal version (standing for a neutrino) versus a more inclined, vertical geometry. This inclined geometry could offer an atmospheric muon interpretation
• Figure 5: The different expected survival distances for muon and tau assuming their corresponding energies. The orange range curve has been here updated by a light blue curve, based on earlier articles:fargion2002discovering,fargion2004tau. At $\theta > = 7^o$, or at least $\theta > 5^o$ inclination, an energetic , EeV, atmospheric charmed muon might reach, the deep sea, respectively, nearly $20$ up to $28$ km distances, within the muon survival track distance. Easier possibility to reach at high energy for a more bent array $\theta > > 7^o$