Flavor Structure of the Cosmic-Ray Electron/Positron Excesses at DAMPE [HEAP]


The Dark Matter Particle Explorer (DAMPE) satellite detector newly announced its first result for measuring the cosmic-ray electron/positron (CRE) energy spectrum up to 4.6TeV, including a peak-like event excess around 1.4TeV. We observe a sizable hidden excess in the DAMPE CRE spectrum over a fairly wide region (0.6-1.1)TeV, which has a non-peak-like structure. We find that this new excess can be explained by a set of 1.4TeV $\mu^\pm$ events with subsequent decays into $e^\pm$ plus neutrinos. To explain this new excess together with the 1.4TeV peak, we show that the flavor structure of the original lepton final-state produced by the dark matter (DM) annihilations (or other mechanism) should have a composition ratio $N_e : (N_\mu + \frac {1}{6} N_\tau) \approx 1:12.7$. We point out some simple realizations, including the simplest case, $N_e : N_\mu : N_\tau \approx 1:12.7:0$. We further discuss the implications for the flavor-related DM model buildings.

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S. Ge and H. He
Fri, 8 Dec 17

Comments: 6 pages, 3 figures