No Arabic 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 $e^pm W^mp$. We find that a DM lifetime $tau_{DM} sim 10^{28}$ s can fit the DAMPE peak with a DM mass $m_{DM}=3$ TeV. 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 ($Z^prime$ boson), and its thermal relic abundance is controlled by only three free parameters: $m_{DM}$, the $U(1)_{B-L}$ gauge coupling ($alpha_{BL}$), and the $Z^prime$ boson mass ($m_{Z^prime}$). For $m_{DM}=3$ TeV, the rest of the parameters are restricted to be $m_{Z^prime}simeq 6$ TeV and $0.00807 leq alpha_{BL} leq 0.0149$, in order to reproduce the observed DM relic density and to avoid the Landau pole for the running $alpha_{BL}$ below the Planck scale. This allowed region will be tested by the search for a $Z^prime$ boson resonance at the future Large Hadron Collider.
We consider the possibility of having a MeV right-handed neutrino as a dark matter constituent. The initial reason for this study was the 511 keV spectral line observed by the satellite experiment INTEGRAL: could it be due to an interaction between dark matter and baryons? Independently of this, we find a number of constraints on the assumed right-handed interactions. They arise in particular from the measurements by solar neutrino experiments. We come to the conclusion that such particles interactions are possible, and could reproduce the peculiar angular distribution, but not the rate of the INTEGRAL signal. However, we stress that solar neutrino experiments are susceptible to provide further constraints in the future.
We study the possibility of improving the constraints on the lifetime of gravitino dark matter in scenarios with bilinear R-parity violation by estimating the amount of cosmic-ray antideuterons that can be produced in gravitino decays. Taking into account all different sources of theoretical uncertainties, we find that the margin of improvement beyond the limits already set by cosmic-ray antiproton data are quite narrow and unachievable for the next generation of experiments. However, we also identify more promising energy ranges for future experiments.
In this paper, we will discuss a specific case that the dark matter particles annihilate into right-handed neutrinos. We calculate the predicted gamma-ray excess from the galactic center and compare our results with the data from the Fermi-LAT. An approximately 10-60 GeV right-handed neutrino with heavier dark matter particle can perfectly explain the observed spectrum. The annihilation cross section $langle sigma v rangle$ falls within the range $0.5$-$4 times 10^{-26} text{ cm}^3/text{s}$, which is roughly compatible with the WIMP annihilation cross section.
We propose a decaying cold dark matter model to explain the excess of electron recoil observed at the XENON1T experiment. In this scenario, the daughter dark matter from the parent dark matter decay easily obtains velocity large enough to saturate the peak of the electron recoil energy around 2.5 keV, and the observed signal rate can be fulfilled by the parent dark matter with a mass of order 10-200 MeV and a lifetime larger than the age of Universe. We verify that this model is consistent with experimental limits from dark matter detections, Cosmic Microwave Background and Large Scale Structure experiments.
Very light right-handed (RH) sneutrinos in the Next-to-Minimal Supersymmetric Standard Model can be viable candidates for cold dark matter. We investigate the prospects for their direct detection, addressing their compatibility with the recent signal observed by the CoGeNT detector, and study the implications for Higgs phenomenology. We find that in order to reproduce the correct relic abundance very light RH sneutrinos can annihilate into either a fermion-antifermion pair, very light pseudoscalar Higgses or RH neutrinos. If the main annihilation channel is into fermions, we point out that RH sneutrinos could naturally account for the CoGeNT signal. Furthermore, the lightest Higgs has a very large invisible decay width, and in some cases the second-lightest Higgs too. On the other hand, if the RH sneutrino annihilates mostly into pseudoscalars or RH neutrinos the predictions for direct detection are below the current experimental sensitivities and satisfy the constraints set by CDMS and XENON. We also calculate the gamma ray flux from RH sneutrino annihilation in the Galactic centre, including as an interesting new possibility RH neutrinos in the final state. These are produced through a resonance with the Higgs and the resulting flux can exhibit a significant Breit-Wigner enhancement.