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The DArk Matter Particle Explorer (DAMPE), a high energy cosmic ray and $gamma$-ray detector in space, has recently reported the new measurement of the total electron plus positron flux between 25 GeV and 4.6 TeV. A spectral softening at $sim0.9$ TeV and a tentative peak at $sim1.4$ TeV have been reported. We study the physical implications of the DAMPE data in this work. The presence of the spectral break significantly tightens the constraints on the model parameters to explain the electron/positron excesses. The spectral softening can either be explained by the maximum acceleration limits of electrons by astrophysical sources, or a breakdown of the common assumption of continuous distribution of electron sources at TeV energies in space and time. The tentive peak at $sim1.4$ TeV implies local sources of electrons/positrons with quasi-monochromatic injection spectrum. We find that the cold, ultra-relativistic $e^+e^-$ winds from pulsars may give rise to such a structure. The pulsar is requird to be middle-aged, relatively slowly-rotated, mildly magnetized, and isolated in a density cavity. The annihilation of DM particles ($m_{chi}sim1.5$ TeV) into $e^+e^-$ pairs in a nearby clump or an over-density region may also explain the data. In the DM scenario, the inferred clump mass (or density enhancement) is about $10^7-10^8$ M$_odot$ (or $17-35$ times of the canonical local density) assuming a thermal production cross section, which is relatively extreme compared with the expectation from numerical simulations. A moderate enhancement of the annihilation cross section via, e.g., the Sommerfeld mechanism or non-thermal production, is thus needed.
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Recent high-energy cosmic $e^pm$ measurement from the DArk Matter Particle Explorer (DAMPE) satellite confirms the deviation of total cosmic ray electron spectrum above 700-900 GeV from a simple power law. In this paper we demonstrate that the cascade decay of dark matter (DM) can account for DAMPEs TeV $e^+e^-$ spectrum. We select the least constraint DM decay channel into four muons as the benchmark scenario, and perform an analysis with propagation variance in both DM signal and the Milky Ways electron background. The best-fit of the model is obtained for joint DAMPE, Fermi-Large Area Telescope (Fermi-LAT), High Energy Stereoscopic System (HESS), high energy electron data sets, and with an $mathcal{O}(10^{26})$ second decay lifetime, which is consistent with existing gamma ray and cosmic microwave background limits. We compare the spectral difference between the cascade decay of typical final-state channels. The least constrained $4mu$ channels give good fits to the electron spectrums TeV scale down-turn, yet their low energy spectrum has tension with sub-TeV positron data from AMS02. We also consider a three-step cascade decay into eight muons, and also a gamma-ray constrained $4mu,4b$ mixed channel, to demonstrate that a further softened cascade decay signal would be required for the agreement with all the data sets.
The DArk Matter Particle Explorer (DAMPE) experiment has recently announced the first results for the measurement of total electron plus positron fluxes between 25 GeV and 4.6 TeV. A spectral break at about 0.9 TeV and a tentative peak excess around 1.4 TeV have been found. However, it is very difficult to reproduce both the peak signal and the smooth background including spectral break simultaneously. We point out that the numbers of events in the two energy ranges (bins) close to the 1.4 TeV excess have $1sigma$ deficits. With the basic physics principles such as simplicity and naturalness, we consider the $-2sigma$, $+2sigma$, and $-1sigma$ deviations due to statistical fluctuations for the 1229.3~GeV bin, 1411.4~GeV bin, and 1620.5~GeV bin. Interestingly, we show that all the DAMPE data can be explained consistently via both the continuous distributed pulsar and dark matter interpretations, which have $chi^{2} simeq 17.2 $ and $chi^{2} simeq 13.9$ (for all the 38 points in DAMPE electron/positron spectrum with 3 of them revised), respectively. These results are different from the previous analyses by neglecting the 1.4 TeV excess. At the same time, we do a similar global fitting on the newly released CALET lepton data, which could also be interpreted by such configurations. Moreover, we present a $U(1)_D$ dark matter model with Breit-Wigner mechanism, which can provide the proper dark matter annihilation cross section and escape the CMB constraint. Furthermore, we suggest a few ways to test our proposal.
The hardening and softening features in the DAMPE proton spectrum are very likely to be originated from a nearby supernova remnant (SNR). The proton spectrum from the nearby SNR is required to be very hard below $approx10$ TeV. To reproduce this feature, we illustrate that anomalously slow-diffusion zone for cosmic rays (CRs) must be existed in the local interstellar medium (ISM) after also taking the dipole anisotropy of CRs into account. Assuming that the diffusion coefficient is homogeneous in the nearby ISM, we show that the diffusion coefficient is constrained to the magnitude of $10^{26}$ cm$^2$ s$^{-1}$ when normalized to 1 GeV, which is about 100 times smaller than the average value in the Galaxy. We further discuss the spatial distribution of the slow diffusion and find two distinct possibilities. In one case, the SNR is several hundred of parsecs away from the solar system, meanwhile both the SNR and the solar system are required to be included in a large slow-diffusion zone. The homogeneous diffusion belongs to this case. In the other case, the SNR is very close with a distance of $sim50$ pc and the slow-diffusion zone is only limited around the SNR. The required diffusion coefficient is further smaller in the latter case. This work provides a new way of studying the CR diffusion in the local ISM.
The DArk Matter Particle Explorer (DAMPE) is an orbital experiment aiming at searching for dark matter indirectly by measuring the spectra of photons, electrons and positrons originating from deep space. The BGO electromagnetic calorimeter is one of the key sub-detectors of the DAMPE, which is designed for high energy measurement with a large dynamic range from 5 GeV to 10 TeV. In this paper, some methods for energy correction are discussed and tried, in order to reconstruct the primary energy of the incident electrons. Different methods are chosen for the appropriate energy ranges. The results of Geant4 simulation and beam test data (at CERN) are presented.
We explore interpretations of the anomaly observed by H1 and ZEUS at HERA in deep-inelastic e^+ p scattering at very large Q^2. We discuss the possibilities of new effective interactions and the production of a narrow state of mass 200 GeV with leptoquark couplings. We compare these models with the measured Q^2 distributions: for the contact terms, constraints from LEP2 and the Tevatron allow only a few choices of helicity and flavour structure that could roughly fit the HERA data. The data are instead quite consistent with the Q^2 distribution expected from a leptoquark state. We study the production cross sections of such a particle at the Tevatron and at HERA. The absence of a signal at the Tevatron disfavours the likelihood that any such leptoquark decays only into e^+ q. We then focus on the possibility that the leptoquark is a squark with R-violating couplings. In view of the present experimental limits on such couplings, the most likely production channels are e^+d -> scharm_L or perhaps e^+d->stop, with e^+s->stop a more marginal possibility. Possible tests of our preferred model include the absence both of analogous events in e^- p collisions and of charged current events, and the presence of detectable cascade decays whose kinematical signatures we discuss. We also discuss the possible implications for K->pi nu nubar, neutrinoless double-beta decay, the Tevatron and for e^+ e^- ->q qbar and neutralinos at LEP2.
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