Revisiting Multi-Component Dark Matter with New AMS-02 Data

We revisit the multi-component leptonically decaying dark matter (DM) scenario to explain the possible electron/positron excesses with the recently updated AMS-02 data. We find that both the single- and two-component DM models can fit the positron fraction and $e^+/e^-$ respective fluxes, in which the two-component ones provide better fits. However, for the single-component models, the recent AMS-02 data on the positron fraction limit the DM cutoff to be smaller than 1 TeV, which conflicts with the high-energy behavior of the AMS-02 total $e^++e^-$ flux spectrum, while the two-component DM models do not possess such a problem. We also discuss the constraints from the Fermi-LAT measurement of the diffuse $\gamma$-ray spectrum. We show that the two-component DM models are consistent with the current DM lifetime bounds. In contrast, the best-fit DM lifetimes in the single-component models are actually excluded.
Comment: 18 pages, 2 figures, revised version accepted for publication in PRD