Astrophysical flux of dark particles as a solution to the KM3NeT and IceCube tension over KM3-230213A

We entertain the possibility that transient astrophysical sources can produce a flux of dark particles that induce ultra-high-energy signatures at neutrino telescopes such as IceCube and KM3NeT. We construct scenarios where such ``dark flux" can produce meta-stable dark particles inside the Earth that subsequently decay to muons, inducing through-going tracks in large-volume neutrino detectors. We consider such a scenario in light of the $\mathcal{O}(70)$~PeV ultra-high-energy muon observed by KM3NeT and argue that because of its location in the sky and the strong geometrical dependence of the signal, such events would not necessarily have been observed by IceCube. Our model relies on the upscattering of a new particle $X$ onto new metastable particles that decay to dimuons with decay lengths of $\mathcal{O}(100)$~km. This scenario can explain the observation by KM3NeT without being in conflict with the IceCube data.