DAMPE excess from decaying right-handed neutrino dark matter

Abstract

The flux of high-energy cosmic-ray electrons plus positrons recently measured by the DArk Matter Particle Explorer (DAMPE) exhibits a tentative peak excess at an energy of around 1.4 TeV. In this paper, we consider the minimal gauged U(1)B-L model with a right-handed neutrino (RHN) dark matter (DM) and interpret the DAMPE peak with a late-time decay of the RHN DM into e±W∓. We find that a DM lifetime τDM ~ 1028s can fit the DAMPE peak with a DM mass mDM = 3TeV. This favored lifetime is close to the current bound on it by Fermi-LAT, our decaying RHN DM can be tested, once the measurement of cosmic gamma ray flux is improved. The RHN DM communicates with the Standard Model particles through the U(1)B-L gauge boson (Z′ boson), and its thermal relic abundance is controlled by only three free parameters: mDM, the U(1)B-L gauge coupling (αBL), and the Z′ boson mass (mZ′). For mDM = 3TeV, the rest of the parameters are restricted to be mZ′≈ 6TeV and 0.00807 ≤ αBL ≤ 0.0149, in order to reproduce the observed DM relic density and to avoid the Landau pole for running αBL below the Planck scale. This allowed region will be tested by the search for a Z′ boson resonance at the future Large Hadron Collider.