Direct detection of Higgs-portal dark matter at the LHC

Abstract: We consider the process in which a Higgs particle is produced in association with jets and show that monojet searches at the LHC already provide interesting constraints on the invisible decays of a 125 GeV Higgs boson. Using the existing monojet searches performed by CMS and ATLAS, we show the 95% confidence level limit on the invisible Higgs decay rate is of the order of the total Higgs production rate in the Standard Model. This limit could be significantly improved when more data at higher center of mass energies are collected, provided systematic errors on the Standard Model contribution to the monojet background can be reduced. We also compare these direct constraints on the invisible rate with indirect ones based on measuring the Higgs rates in visible channels. In the context of Higgs portal models of dark matter, we then discuss how the LHC limits on the invisible Higgs branching fraction impose strong constraints on the dark matter scattering cross section on nucleons probed in direct detection experiments.

• The paper demonstrates that monojet events at the LHC effectively probe invisible Higgs decays linked to dark matter.
• The analysis leverages CMS and ATLAS search strategies to impose stringent limits on the Higgs boson’s invisible decay rate.
• These findings refine Higgs-portal dark matter models by directly impacting constraints on dark matter-nucleon scattering cross-sections.

Overview of the Paper "Direct detection of Higgs--portal dark matter at the LHC"

This paper addresses the investigation of a Higgs boson's possible invisible decay modes through the production of Higgs particles at the Large Hadron Collider (LHC) and the subsequent analysis of these events to constrain dark matter models, particularly the Higgs-portal models. The authors utilize the monojet search strategies deployed by the CMS and ATLAS collaborations to place constraints on the invisible decay rate of the Higgs boson and, consequently, on the interaction between the Higgs boson and potential dark matter candidates.

Summary of Main Points

1. Higgs Production and Decay at the LHC: The research focuses on the detection of Higgs bosons produced in association with jets, specifically monojet events, where the Higgs decays into non-interacting particles (invisible decays), which are indicative of potential linkages to dark matter candidates. It is acknowledged that such invisible particles do not interact with the detector, creating unique challenges for their detection.
2. Invisible Higgs Decay Constraints: The study provides an analysis based on existing CMS and ATLAS search results, which have explored monojet events. These searches place the 95% confidence level limit on the Higgs' invisible decay rate at a magnitude comparable to the Higgs production rate predicted by the Standard Model (SM).
3. Implications for Dark Matter Models: In the context of Higgs-portal models, the paper elaborates on how limitations on the Higgs' invisible branching fractions can severely restrict the dark matter scattering cross-section on nucleons, as investigated in direct detection experiments. The Higgs-portal model perceives the Higgs boson as a mediator in the annihilation and scattering processes of dark matter, forming a crucial interface between collider experiments and the quest for direct dark matter detection.
4. Monojet Event Analysis Techniques: The study investigates the sensitivity of different monojet searches and how systematic errors from the SM's contribution to the monojet background might be refined for more stringent constraints as additional data becomes available at higher energies.
5. Experimental Details and Results: The research includes detailed simulations of the process in which a Higgs boson is produced alongside jets and decays into invisible particles. The analysis parameters include jet transverse momentum cuts and detector acceptance criteria specific to the LHC's environment.
6. Comparison with Indirect Constraints: A comparison between the direct constraints on the invisible rate obtained from monojet searches with indirect ones inferred from Higgs rate measurements in visible decay channels is made, highlighting the relevance of monojet constraints for enhanced Higgs production rates beyond the SM predictions.

Implications and Future Prospects

The results from this paper have significant implications for both experimental and theoretical physics. They offer:

• Theoretical Insight: This research enhances our understanding of non-standard decay processes involving the Higgs boson and sheds light on how such processes can be intertwined with dark matter theoretical frameworks, providing a method to explore physics beyond the SM.
• Practical Applications: The paper demonstrates that existing experimental setups and data can be leveraged to place constraints on exotic physical phenomena, including potential dark matter interactions, which commonly remain elusive to traditional detection methodologies.
• Future Prospects: As further data from the LHC become available, there exists substantial potential to enhance the precision of these invisible decay constraints, improving our understanding of the Higgs boson's role within and beyond the current theoretical frameworks.

In conclusion, this paper offers valuable insights into Higgs boson detection in the context of invisible decays and discusses their interface with dark matter, utilizing the LHC as an essential tool in the ongoing exploration of theoretical and experimental high-energy physics. It sets the stage for further empirical investigations that can refine our understanding of the universe's fundamental constituents.