Decaying Leptophilic Dark Matter at IceCube

TL;DR

This paper proposes that high-energy neutrinos detected by IceCube can be explained by a combination of astrophysical sources and leptophilic dark matter decays, with models that do not require extremely small couplings.

Contribution

It introduces two elementary particle models for dark matter decay that fit IceCube data without tiny couplings and discusses the spectral features consistent with a cutoff around 100 TeV.

Findings

Compatibility of models with IceCube data when astrophysical flux has a 100 TeV cutoff

Dark matter decay can account for PeV neutrinos if a spectral cutoff is observed

Purely astrophysical explanations remain possible without a cutoff

Abstract

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.