Supersymmetric Resonant Dark Matter: a Thermal Model for the AMS-02
  Positron Excess
  We construct a thermal dark matter model with annihilation mediated by a
resonance to explain the positron excess observed by PAMELA, Fermi-LAT and
AMS-02, while satisfying constraints from cosmic microwave background (CMB)
measurements. The challenging requirement is that the resonance has twice the
dark matter mass to one part in a million. We achieve this by introducing an
$SU(3)_f$ dark flavor symmetry that is spontaneously broken to $SU(2)_f \times
U(1)_f$. The resonance is the heaviest state in the dark matter flavor
multiplet and the required mass relation is protected by the vacuum structure
and supersymmetry from radiative corrections. The pseudo-Nambu Goldstone Bosons
(PNGB's) from the dark flavor symmetry breaking can be slightly lighter than
one GeV and dominantly decay into two muons just from kinematics, with
subsequent decay into positrons. The PNGB's are produced in resonant dark
matter semi-annihilation, where two dark matter particles annihilate into an
anti-dark matter particle and a PNGB. The dark matter mass in our model is
constrained to be below around 1.9 TeV from fitting thermal relic abundance,
AMS-02 data and CMB constraints. The superpartners of Standard Model (SM)
particles can cascade decay into a light PNGB along with SM particles, yielding
a correlated signal of this model at colliders. One of the interesting
signatures is a resonance of a SM Higgs boson plus two collimated muons, which
has superb discovery potential at LHC Run 2.
