Implications of LHC searches for Higgs--portal dark matter (1112.3299v3)

Abstract: The search for the a Standard Model Higgs boson at the LHC is reaching a critical stage as the possible mass range for the particle has become extremely narrow and some signal at a mass of about 125 GeV is starting to emerge. We study the implications of these LHC Higgs searches for Higgs portal models of dark matter in a rather model independent way. Their impact on the cosmological relic density and on the direct detection rates are studied in the context of generic scalar, vector and fermionic thermal dark matter particles. Assuming a sufficiently small invisible Higgs decay branching ratio, we find that current data, in particular from the XENON experiment, essentially exclude fermionic dark matter as well as light, i.e. with masses below 50 GeV, scalar and vector dark matter particles. Possible observation of these particles at the planned upgrade of the XENON experiment as well in collider searches is discussed.

• The paper analyzes LHC Higgs search implications for scalar, vector, and fermionic Higgs-portal dark matter, showing current data rules out light fermionic and some light scalar/vector DM particles.
• Using a model-independent framework, the study applies cosmological relic density and direct detection constraints from experiments like XENON to constrain Higgs-portal dark matter models.
• The findings highlight challenging detection thresholds for future direct detection and collider experiments, especially for heavier dark matter particles and those interacting via invisible Higgs decays.

Higgs-Portal Dark Matter: Implications from the LHC

This paper explores the ramifications of the LHC Higgs searches for Higgs-portal models of dark matter, emphasizing a model-independent analysis of scalar, vector, and fermionic thermal dark matter (DM) particles. The paper presents a comprehensive evaluation of how recent LHC findings, particularly signals indicating a Higgs boson around 125 GeV, affect the viability of these DM models.

Main Findings

The investigation employs a model-independent framework to explore the constraints placed by cosmological relic density and direct detection experiments, particularly XENON, on Higgs-portal dark matter models. In particular, the authors posit that if the invisible Higgs decay branching ratio is sufficiently small, fermionic dark matter and lighter scalar and vector dark matter particles (those with masses below approximately 60 GeV) are effectively ruled out by current data.

Results and Analysis

1. Higgs-Portal Dark Matter Models: The paper considers three conventional scenarios for Higgs-portal dark matter involving scalar, vector, and Majorana fermion DM particles. These particles interact with Standard Model (SM) fields only through the Higgs portal and are stabilized by a $Z_2$ symmetry.
2. Constraints from Direct Detection: The paper places constraints on these models using data from the XENON100 experiment. It demonstrates the exclusion of fermionic DM and light scalar and vector DMs based on their inability to meet direct detection and relic density constraints simultaneously.
3. Invisible Higgs Decays and Collider Implications: The potential observation of light DM through invisible Higgs decays is constrained by LHC data, suggesting that such particles would need a significantly reduced coupling to remain viable. Additionally, DM particles heavier than about 80 GeV can evade current detection limits but remain subject to future experimental upgrades.

Implications and Future Directions

The paper emphasizes the implications for Higgs physics at the LHC and future collider experiments. It is noted that if DM particles must evade the constraint of an invisible Higgs decay branching ratio, direct evidence of DM through collider experiments may be necessitated, specifically through processes like vector boson fusion or associated Higgs production, which challenge detection efforts given low cross sections.

Theoretical predictions indicate challenging detection thresholds for future upgrades such as XENON1T and collider experiments. These findings highlight the need for continued refinement in detection methods and the potential development of new strategies to unveil the properties of these elusive particles.

Conclusion

The paper concludes by affirming the exclusion of Higgs-portal models with light fermionic or scalar/vector dark matter classes and suggests that these findings probe nearly the entire spectrum of such models. It calls for refined experimental pursuits at upgraded facilities to potentially detect and differentiate between vector and scalar dark matter cases conclusively.

This paper contributes significantly to the discourse on dark matter searches, bridging particle physics and cosmology, and emphasizes the importance of experimental advancements in understanding dark sector interactions mediated through the Higgs boson.