Triplet Dark Matter from leptogenesis
  A triplet dark matter candidate from thermal leptogenesis is considered with
building a model. The model is based on the standard two Higgs doublet model
and seesaw mechanism with Higgs triplets. The parameters (couplings and masses)
are adjusted for the observed small neutrino mass and the leptogenesis. Dark
matter particles can annihilate and decay in this model. The time evolution of
the dark matter number is governed by (co)annihilations in the expanding
universe, and its mass is constrained by the observed relic density. The dark
matter can decay into final states with three leptons (two charged leptons and
one neutrino). We investigate whether the decay in the galaxy can account for
cosmic ray anomalies in the positron and electron spectrum. A noticeable point
is that if the dark matter decays into each lepton with different branching
ratios, cosmic ray anomalies in AMS-02 measurements of the positron fraction
and the Fermi LAT measurements of the electrons-plus-positrons flux could be
simultaneously accounted for from its decay products. The leptogenesis within
this model is studied in an appendix.
