7,694 research outputs found
Stable Large-Scale Perturbations in Interacting Dark-Energy Model
It is found that the evolutions of density perturbations on the super-Hubble
scales are unstable in the model with dark-sector interaction proportional
to the energy density of cold dark matter (CDM) and constant equation
of state parameter of dark energy . In this paper, to avoid the
instabilities, we suggest a new covariant model for the energy-momentum
transfer between DE and CDM. Then we show that the the large-scale
instabilities of curvature perturbations can be avoided in our model in the
universe filled only by DE and CDM. Furthermore, by including the additional
components of radiation and baryons, we calculate the dominant non-adiabatic
modes in the radiation era and find that the modes grow in the power law with
exponent at the order of unit.Comment: 14 pages, 2 figures. arXiv admin note: substantial text overlap with
arXiv:1110.180
Lepton-portal Dark Matter in Hidden Valley model and the DAMPE recent results
We study the recent cosmic ray excess reported by DAMPE in a Hidden
Valley Model with lepton-portal dark matter. We find the electron-portal can
account for the excess well and satisfy the DM relic density and direct
detection bounds, while electron+muon/electron+muon+tau-portal suffers from
strong constraints from lepton flavor violating observables, such as . We also discuss possible collider signatures of our model, both at the LHC
and a future 100 TeV hadron collider.Comment: invited by Science China, accepted versio
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