Scalar Split WIMPs in the Future Direct Detection Experiments

Abstract: We consider a simple renormalizable dark matter model consisting of two real scalars with a mass splitting $\delta$, interacting with the SM particles through the Higgs portal. We find a viable parameter space respecting all the bounds imposed by invisible Higgs decay experiments at the LHC, the direct detection experiments by XENON100 and LUX and the dark matter relic abundance provided by WMAP and Planck. Despite the singlet scalar dark matter model that is fragile against the future direct detection experiments, the scalar split model introduced here survives such forthcoming bounds. We emphasize on the role of the co-annihilation processes and the mixing effects in this feature. For $m_{\text{DM}} \sim 63$ GeV in this model we can explain as well the observed gamma-ray excess in the analyses of the Fermi-LAT data at Galactic latitudes $2^{\circ} \leq |b| \leq 20^{\circ}$ and Galactic longitudes $|l| < 20^{\circ}$.