http://arxiv.org/abs/1712.00372
Recently, DAMPE has released its first results on the high-energy cosmic-ray electrons and positrons (CREs) from about $25 \mathrm{GeV}$ to $4.6 \mathrm{TeV}$, which directly detect a break at $\sim 1 \mathrm{TeV}$. This result gives us an excellent opportunity to study the source of the CREs excess. We first reproduce the proton, helium flux and $\bar{p}/p$ ratio data from AMS-02 and CREAM (above $\sim \mathrm{TeV}$) by global fitting (Step I), which determine not only the propagation parameters but also the primary source parameters of proton and helium spectra. With the best fitting parameters from Step I, we do global fitting on the CREs flux from DAMPE and positron flux from AMS-02 (Step II). In this step, we consider two separate scenarios (pulsar and dark matter annihilation via leptonic channels) to construct the bump ($\gtrsim 100 \mathrm{GeV}$) and the break at $\sim 1 \mathrm{TeV}$. The result shows: (i) in pulsar scenario, the spectral index of the injection should be $\nu_{psr} \sim 0.68$ and the cut-off should be $R_{c} \sim 660 \mathrm{GV}$; (ii) in dark matter scenario, the dark matter particle’s mass is $m_{\chi} \sim 1208 \mathrm{GeV}$ and the cross section is $\langle \sigma v \rangle \sim 1.48 \times 10^{-23} \mathrm{cm}^{3} \mathrm{s}^{-1}$. Moreover, in the dark matter scenario, the $\tau \bar{\tau}$ annihilation channel is highly suppressed. If we deduct the line spectral signal at $\sim 1.4 \mathrm{TeV}$, the CREs data from DAMPE favors the dark matter interpretation. Furthermore, we present two simple dark matter models to explain the DAMPE results by introducing an SM singlet scalar $S$ as dark matter particle. In one model, we introduce a doublet scalar $H’$ as a mediator, while in the other model we introduce a pair of vector-like fermions $(XE, XE^c)$. In these models, the real scalar dark matter can annihilate dominantly into the charged lepton pairs.
J. Niu, T. Li, R. Ding, et. al.
Mon, 4 Dec 17
45/72
Comments: 11 pages, 2 figures. arXiv admin note: text overlap with arXiv:1705.11089; text overlap with arXiv:1409.6248, arXiv:1410.0171 by other authors