Light dark matter in a minimal extension with two additional real singlets

Abstract: The direct searches for heavy scalar dark matter with a mass of order 100 GeV are much more sensitive than for light dark matter of order 1 GeV. The question arises whether dark matter could be light and has escaped detection so far. We study a simple extension of the Standard Model with two additional real singlets. We show that this simple extension may provide the observed relic dark matter density, does neither disturb big-bang nucleosynthesis nor the cosmic microwave background radiation observations and fulfills the conditions of clumping behavior for different sizes of galaxies. The potential of one Standard Model-like Higgs-boson doublet and the two singlets gives rise to a changed Higgs phenomenology, in particular, an enhanced invisible Higgs-boson decay rate is expected, detectable by missing transversal momentum searches at the ATLAS and CMS experiments at CERN.