Decaying Dark Atom constituents and cosmic positron excess
  We present a scenario where dark matter is in the form of dark atoms that can
accomodate the experimentally observed excess of positrons in PAMELA and AMS-02
while being compatible with the constraints imposed on the gamma-ray flux from
Fermi/LAT. This scenario assumes that the dominant component of dark matter is
in the form of a bound state between a helium nucleus and a $-2$ particle and a
small component is in the form of a WIMP-like dark atom compatible with direct
searches in underground detectors. One of the constituents of this WIMP-like
state is a $+2$ metastable particle with a mass of 1 TeV or slightly below that
by decaying to $e^+e^+$, $\mu^+ \mu^+$ and $\tau^+ \tau^+$ produces the
observed positron excess. These decays can naturally take place via GUT
interactions. If it exists, such a metastable particle can be found in the next
run of LHC. The model predicts also the ratio of leptons over baryons in the
Universe to be close to -3.
