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KM3NeT 220 PeV event: A neutrino messenger from the grand unification scale?

Vernon Barger*

  • *Contact author: barger@pheno.wisc.edu
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APS Open Sci. 1, 000180 – Published 22 October, 2026

DOI: https://doi.org/10.1103/51px-xpdh

Abstract

The 220 PeV neutrino KM3-230213A, in tension with IceCube and Auger unless the underlying spectrum is narrow (a ∼2σ upward fluctuation in any case), admits a two-body reading: relic decay X→νν¯ with mX≈4.4×108 GeV. Consistency with neutrino and γ-ray bounds sets τ/f≈1029–1030s, lifetime over relic fraction. For a flavored 1S0 onium, the operator scale lands in the Majorana-mass range of unified models: One Higgs insertion gives a singlet mediator, Mmed/|C7|1/3≈1014–1016 GeV across the allowed relic fraction; two give the seesaw window; Dirac or Majorana neutrinos select the branch. We give the construction and its decisive tests.

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APS Open Sci. 1, 000180– Published 22 October, 2026
Vol. 1
  • Received 12 July 2026
  • Accepted 2 September 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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