AMS02 positron excess from decaying fermion DM with local dark gauge symmetry

Positron excess observed by PAMELA, Fermi and AMS02 may be due to dark matter (DM) pair annihilation or decay dominantly into muons. In this paper, we consider a scenario with thermal fermionic DM (χ  ) with mass ∼O(1–2) TeV∼O(1–2) TeV decaying into a dark Higgs (ϕ  ) and an active neutrino (νaνa) instead of the SM Higgs boson and νaνa. We first present a renormalizable model for this scenario with local dark U(1)XU(1)X gauge symmetry, in which the DM χ can be thermalized by Higgs portal and the gauge kinetic mixing. Assuming the dark Higgs (ϕ  ) mass is in the range 2mμ