New Constraints on Higgs-portal Scalar Dark Matter

The simplest Higgs-portal scalar dark matter model, in which a real scalar singlet is added to the standard model, has been revisited, by taking into account the constraints from perturbativity, electroweak vacuum stability in the early Universe, dark matter direct detection, and Higgs invisible decay at the LHC. We show that the {\it resonant mass region} is totally excluded and the {\it high mass region} is reduced to a narrow window $1.1$ ~TeV $\leq m_{s} \leq$ $2.55$~ TeV, which is slightly reduced to $1.1$~TeV $\leq m_{s} \leq$ $2.0$~ TeV if the perturbativity is further imposed. This {\it high mass range} can be fully detected by the Xenon 1T experiment.