We present a novel interpretation of IceCube high energy neutrino events
(with energy larger than 60 TeV) in terms of an extraterrestrial flux due to
two different contributions: a flux originated by known astrophysical sources
and dominating IceCube observations up to few hundreds TeV, and a new flux
component where the most energetic neutrinos come from the leptophilic
three-body decays of dark matter particles with a mass of few PeV. Differently
from other approaches, we provide two examples of elementary particle models
that do not require extremely tiny coupling constants. We find the
compatibility of the theoretical predictions with the IceCube results when the
astrophysical flux has a cutoff of the order of 100 TeV (broken power law). In
this case the most energetic part of the spectrum (PeV neutrinos) is due to an
extra component such as the decay of a very massive dark matter component. Due
to the low statistics at our disposal we have considered for simplicity the
equivalence between deposited and neutrino energy, however such approximation
does not affect dramatically the qualitative results. Of course, a purely
astrophysical origin of the neutrino flux (no cutoff in energy below the PeV
scale - unbroken power law) is still allowed. If future data will confirm the
presence of a sharp cutoff above few PeV this would be in favor of a dark
matter interpretation.Comment: 19 pages, 3 figures. Version published in JCAP. The analysis was
performed in terms of the number of neutrino events instead of the neutrino
flux, using a multi-Poisson likelihood approac
