Leptophilic Dark Matter from the Lepton Asymmetry
  We present a model of weak scale Dark Matter (DM) where the thermal DM
density is set by the lepton asymmetry due to the presence of higher dimension
lepton violating operators. In these models there is generically a separation
between the annihilation cross-section responsible for the relic abundance
(through lepton violating operators) and the annihilation cross-section that is
relevant for the indirect detection of DM (through lepton preserving
operators). Due to this separation, there is a perceived boost in the
annihilation cross-section in the galaxy today relative to that derived for
canonical thermal freeze-out. This results in a natural explanation for the
observed cosmic ray electron and positron excesses, without resorting to a
Sommerfeld enhancement. Generating the indirect signals also sets the magnitude
of the direct detection cross-section which implies a signal for the next
generation of experiments. More generically these models motivate continued
searches for DM with apparently non-thermal annihilation cross-sections. The DM
may also play a role in radiatively generating Majorana neutrino masses.
