Constraints on the Real Singlet Scalar Dark Matter Model from Higgs Self-Couplings

Taking the real singlet scalar dark matter model as a representative test case, we examine the constraints imposed on the model's parameter space by Higgs trilinear coupling measurements and perturbative unitarity requirements. For the low dark matter mass regime, the constraining strength delivered by the current highest-precision κ₃ measurement is notably inferior to the exclusion limit derived from perturbative unitarity requirements, while the perturbative unitarity bound itself remains considerably less restrictive than the constraints extracted from the extant experimental upper limit on the Higgs invisible decay branching ratio BRᵢₙᵥ ≤ 0.107. Both the coupling modifiers κ₃ and κ₄ exhibit a well-defined decoupling behavior, with their respective magnitudes monotonically decreasing as the dark matter mass mS increases. As a direct consequence, the corrections to both couplings asymptotically approach zero for dark matter masses in excess of 60 TeV, when the parameter a₂ remains within its perturbative validity domain. Neither existing collider measurements of the Higgs trilinear coupling nor measurements targeted for planned future collider facilities possess the requisite sensitivity to impose more stringent constraints on the model's viable parameter space than the well-established bounds derived from experimental probes of dark matter relic density, invisible Higgs decay signatures, dark matter direct detection, and dark matter indirect detection. Nevertheless, under the scenario that the experimental measurement uncertainty of κ₃ reaches the O(0.1%) scale or lower, non-negligible constraints acting on a subset of the large mass parameter space associated with the WIMP dark matter scenario can be expected.