  We explain the electron-positron excess reported by the DAMPE collaboration
recently in a radiative Dirac seesaw model where a dark $U(1)_X$ gauge symmetry
can (i) forbid the tree-level Yukawa couplings of three right-handed neutrinos
to the standard model lepton and Higgs doublets, (ii) predict the existence of
three dark fermions for the gauge anomaly cancellation, (iii) mediate a
testable scattering of the lightest dark fermion off the nucleons. Our model
can also accommodate a successful leptogenesis to generate the cosmic baryon
asymmetry.

High Energy Physics - Phenomenology