IceCube Events from Heavy DM decays through the Right-handed Neutrino
  Portal
  The recently observed IceCube PeV events could be due to heavy dark matter
(DM) decay. In this paper, we propose a simple DM model with extra $U(1)_X$
gauge symmetry and bridge it with standard model particles through heavy
right-handed neutrino. The Dirac fermion DM $\chi$ with mass ~5 PeV can
dominantly decay into a dark Higgs ($\phi$), the SM Higgs ($h$) and a neutrino
($\nu$). If the lifetime of $\chi$ is ~O($10^{28}$) sec, the resulting neutrino
flux can fit data consistently. The neutrino flux from $\chi \rightarrow \phi h
\nu$ in our model is softer than the one predicted from $\chi \rightarrow \nu
h$, for example. We also discuss a possible mechanism to produce DM with the
right relic abundance.
