Higgs searches and singlet scalar dark matter: Combined constraints from XENON 100 and the LHC

TL;DR

This work investigates a scalar singlet extension of the Standard Model as a Higgs-portal dark matter scenario, examining how XENON100 direct-detection limits, WMAP relic density, and LHC Higgs searches jointly constrain the model. By detailing the model, nucleon-structure uncertainties, and the invisible Higgs width, it shows that the Higgs invisible decay to singlet dark matter is typically negligible, with notable exceptions at very light DM masses or near $m_S\approx 60$ GeV. Incorporating the latest ATLAS/CMS results, a large swath of parameter space is already excluded, particularly for Higgs masses in the $135$–$155$ GeV range where the predicted spin-independent cross section lies in the $8\times10^{-46}$–$2\times10^{-45}$ cm$^{2}$ window. The analysis highlights a complementary landscape where LHC searches are most sensitive to heavier Higgs scenarios while direct detection probes lighter mass regions, and it discusses potential implications if a Higgs signal around $M_H\sim 145$ GeV is confirmed.

Abstract

XENON100 and the LHC are two of the most promising machines to test the physics beyond the Standard Model. In the meantime, indirect hints push us to believe that the dark matter and Higgs boson could be the two next fundamental particles to be discovered. Whereas ATLAS and CMS have just released their new limits on the Higgs searches, XENON100 obtained very recently strong constraints on DM-proton elastic scattering. In this work, we show that when we combined WMAP and the most recent results of XENON100, the invisible width of the Higgs to scalar dark matter is negligible($\lesssim 10%$), except in a small region with very light dark matter ($\lesssim 10$ GeV) not yet excluded by XENON100 or around 60 GeV where the ratio can reach 50% to 60%. The new results released by the Higgs searches of ATLAS and CMS set very strong limits on the elastic scattering cross section, even restricting it to the region $8 \times 10^{-46} \mrm{cm^2} \lesssim σ_{S-p}^{SI}\lesssim 2 \times 10^{-45} \mrm{cm^{2}}$ in the hypothesis $135 \mrm{GeV} \lesssim M_H \lesssim 155 \mrm{GeV}$.

Figures (8)

• Figure 1: Feynman diagram for the annihilation cross section (left) direct detection scattering (center) and invisible width of the Higgs (right).
• Figure 2: Sigma commutators of the proton with two different phenomenological measurements of $\Sigma_{\pi N}=45 \pm 8$ MeV Koch:1982pu and $64 \pm 7$ MeV Pavan:2001wz. We also showed the mean evaluation from more recent lattice results Young:2009zb (left).
• Figure 3: Spin independent elastic scattering cross section as function of the pion-nucleon sigma-term $\Sigma_{\pi N}$ for a scalar dark matter respecting WMAP constraint: $m_s=90$ GeV, $\lambda_{HS}=0.2$, $m_h=130$ GeV giving $\Omega_S h^2=0.102$. We also represented the central values of the cross section for the lattice simulations Toussaint:2009pz and Young:2009zb labelled "MILC" and "Young" respectively.
• Figure 4: Parameter space allowed in the plane ($\mu_S,\lambda_{HS}$) for different Higgs masses (120, 160, 200 and 500 GeV) taking into account the last XENON100 data and the XENON 1T projection, with different values for the strange structure of the nucleon. We also show the invisible branching fraction of the Higgs boson width (10 and 50 % respectively). See the text for details.
• Figure 5: Maximum Higgs invisible branching ratio as a function of the dark matter mass for different higgs masses taking into account the last XENON100 constraint. We also show an example of invisible branching ratio for $M_H=160$ GeV before taking into account XENON100 constraint.