The KM3NeT collaboration recently reported the detection of an
ultra-high-energy neutrino event, dubbed KM3-230213A. This is the first
observed neutrino event with energy of the order of $\mathcal{O}(100)$PeV, the
origin of which remains unclear. We interprete this high energy neutrino event
results from the Dirac fermion dark matter (DM) $\chi$ decay through the
right-handed (RH) neutrino portal assuming the Type-I seesaw mechanism for
neutrino masses and mixings. Fruthermore, dark matter $\chi$ is assumed to
charged under $U(1)_X$ dark gauge symmetry, which is sponetaneously broken by
the vacuum expectation value of the dark Higgs $\Phi$. In this scenario, the DM
can decay into a pair of Standard Model (SM) particles for $v_\Phi \gg m_\chi$,
which we assume is the case. If the DM mass is around $440$ PeV with a lifetime
$5\times 10^{29}$ sec, it can account for the KM3-230213A event. However, such
heavy DM cannot be produced through the thermal freeze-out mechanism due to
overproduction and violation of unitarity bounds. We focus on the UV freeze-in
production of DM through a dimension-5 operator, which helps in producing the
DM dominantly in the early Universe. We have also found a set of allowed
parameter values that can correctly account for the DM relic density and decay
lifetime required to explain the KM3NeT signal. Moreover, we have generated the
neutrino spectra from the two-body decay using the HDMSpectra package, which
requires the dark Higgs vacuum expectations value (VEV) to be much larger than
the DM mass. Finally, the large value of the dark Higgs field VEV opens up the
possibility of generating GW spectra from cosmic strings. We have found a
reasonable set of parameter values that can address the KM3NeT signal, yield
the correct value of the DM relic density through freeze-in mechanism, and
allow for possible detection of GW at future detectors.

Este artículo explora los viajes en el tiempo y sus implicaciones.

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