Light fermionic/scalar dark matter (DM) (m_DM ~ 8 GeV) neutral under the standard model can be responsible for the Fermi-LAT gamma-ray excesses and the CDMS signals. In order to explain them in a relatively simple framework, we have explored various DM annihilation and scattering processes, discussing important phenomenological constraints coming from particle physics. Assuming that the two independent observations have a common DM origin and the processes arise through a common mediator, DM should annihilate into tau/anti-tau lepton pairs through an s-channel, and scatter with nuclei through a t-channel process to explain the observations. To avoid the p-wave suppression, a new Higgs-like scalar field with a mass of O(1) TeV is necessary as a common mediator of the both processes. We propose a supersymmetric model realizing the scenario.
Date added: Thu, 10 Oct 13