Invisible Higgs Decay as a Probe for Light Dark Matter Produced via Freeze-in at Stronger Coupling

Conceitos essenciais

Light dark matter (DM) with mass above 1 MeV can be produced via freeze-in at stronger coupling, leading to observable Higgs decay into invisible final states with a branching fraction of 10% and below, while simultaneously generating the correct DM relic abundance.

Resumo

• Bibliographic Information: Lebedev, O., Morais, A. P., Oliveira, V., & Pasechnik, R. (2024). Invisible Higgs decay from dark matter freeze-in at stronger coupling. arXiv preprint arXiv:2410.21874v1.
• Research Objective: This paper investigates the possibility of observing "invisible" Higgs decay into light dark matter (DM) within the framework of freeze-in at stronger coupling.
• Methodology: The authors utilize the Boltzmann equation to analyze the evolution of DM number density, considering both scalar and fermionic DM candidates interacting with the Standard Model (SM) through the Higgs portal. They calculate DM production rates from the SM thermal bath at low temperatures, taking into account hadronic contributions by relating the DM annihilation rate to the Higgs decay width into hadrons. The parameter space consistent with the observed DM relic abundance and current experimental constraints is then determined.
• Key Findings: The study reveals that DM masses above 1 MeV are viable and can lead to a significant branching ratio for Higgs decay into invisible final states, potentially reaching up to 10%. This finding holds true for a range of reheating temperatures compatible with cosmological data. Notably, the analysis highlights the importance of considering hadronic production modes, especially for DM masses below the GeV scale.
• Main Conclusions: The authors conclude that there are promising prospects for detecting light non-thermal DM through invisible Higgs decay at future colliders like the FCC and HL-LHC. The study emphasizes the potential of this framework to probe DM masses down to the MeV scale, a range challenging for other detection methods.
• Significance: This research significantly contributes to the field of particle physics by providing a testable framework for exploring light DM scenarios. It highlights the interplay between cosmology, collider physics, and direct detection experiments in the search for DM.
• Limitations and Future Research: The study primarily focuses on minimal Higgs portal models. Exploring more complex DM interactions and extended sectors could reveal further implications for Higgs physics and DM detection strategies. Additionally, investigating the impact of different reheating models on the allowed parameter space could refine the predictions for future experiments.

Estatísticas

The Higgs invisible decay branching ratio is constrained to be below 10% by the LHC.
The HL-LHC aims to achieve a sensitivity of 3% for the Higgs invisible decay branching ratio.
The FCC aims to achieve a sensitivity of 0.3% for the Higgs invisible decay branching ratio.
The lowest reheating temperature consistent with observations is 4 MeV.
The critical QCD temperature (Tc) is approximately 150 MeV.

Citações

"The Higgs boson [1, 2] properties serve as a sensitive probe for new physics."
"The recently proposed option of “freeze-in at stronger coupling” [9] evades this conclusion [10, 11]."
"Our findings indicate that there are good prospects for observing light non-thermal DM via invisible Higgs decay at the LHC and FCC."

Principais Insights Extraídos De

Invisible Higgs decay from dark matter freeze-in at stronger coupling

by Oleg... às arxiv.org 10-30-2024

https://arxiv.org/pdf/2410.21874.pdf

Perguntas Mais Profundas

How would the presence of additional, heavier DM particles impact the production of light DM through freeze-in at stronger coupling and its detectability via Higgs decay?

The presence of additional, heavier DM particles could significantly impact the production of light DM through freeze-in at stronger coupling, depending on the nature of their interactions with the light DM and the Standard Model (SM). Here's a breakdown of possible scenarios:
1. Enhanced Production:

Cascade Decays: Heavier DM particles could decay into lighter DM particles, either directly or through a chain of decays. If these decays occur after the heavier DM has been produced from the thermal bath, they would effectively inject additional light DM into the early universe, potentially enhancing its relic abundance. This could allow for smaller Higgs portal couplings while still achieving the observed DM density, making the invisible Higgs decay signature less prominent.
Co-annihilation: If the mass splitting between the heavier and lighter DM particles is small, co-annihilation processes (where the heavier DM particle annihilates with a SM particle to produce the lighter DM particle) could become important. This would also contribute to the light DM abundance and potentially weaken the correlation between the Higgs portal coupling and the relic density.
2. Suppression of Production:

Competing Channels: If the heavier DM particles also couple to the Higgs boson, they would open up additional decay channels for the Higgs, potentially reducing the branching fraction for Higgs decay into light DM. This could make the invisible Higgs decay signature more challenging to observe.
Thermal Effects: If the heavier DM particles were once in thermal equilibrium with the SM bath, their decoupling and subsequent annihilation could heat the SM bath, potentially impacting the production rate of the lighter DM particles. This effect would depend on the masses and couplings of the heavier DM particles.
Detectability via Higgs Decay:
The detectability of light DM through invisible Higgs decay would depend on the interplay of the above factors. If the production of light DM is enhanced, the Higgs portal coupling could be smaller, making the invisible decay less prominent. Conversely, if the production is suppressed or if competing Higgs decay channels are present, the invisible decay signature would be harder to observe.
Distinguishing Scenarios:
Distinguishing these scenarios would require careful analysis of the Higgs decay branching ratios, as well as searches for direct and indirect signals of both the light and heavier DM particles. Observing a heavier DM candidate with properties consistent with the production of the lighter DM would provide strong evidence for these scenarios.

Could the invisible Higgs decay signature explored in this paper be mimicked by other exotic particles or interactions beyond the Standard Model, and how could these scenarios be distinguished experimentally?

Yes, the invisible Higgs decay signature explored in the paper could be mimicked by other exotic particles or interactions beyond the Standard Model. Here are some examples and ways to distinguish them:
1. Light Neutrinos with Enhanced Couplings:

Mimicry: If neutrinos had stronger-than-expected couplings to the Higgs boson, they could be produced in Higgs decays and escape detection, mimicking the invisible decay signature.
Distinction: This scenario could be challenging to distinguish, as the neutrino interaction rate is extremely low. However, modifications to the Higgs decay width into other channels (like Z bosons) due to the modified Higgs-neutrino coupling could provide indirect evidence. Additionally, future neutrino experiments with enhanced sensitivity might be able to detect subtle deviations from SM predictions.
2. Axion-Like Particles (ALPs):

Mimicry: ALPs are hypothetical particles that interact weakly with SM particles and could be produced in Higgs decays. Depending on their mass and couplings, they could also escape detection, leading to an invisible Higgs decay signature.
Distinction: ALPs can have unique couplings to photons and other SM particles, leading to potential signatures in experiments searching for axion-like particles through their interactions with light and matter. Additionally, the production mechanism of ALPs in the early universe would differ from that of freeze-in DM, potentially leading to different cosmological constraints.
3. Hidden Sector Particles:

Mimicry: Theories with hidden sectors often predict new particles that interact very weakly with the SM. These particles could be produced in Higgs decays and escape detection, mimicking the invisible decay signature.
Distinction: Hidden sector particles might interact with each other through new forces, leading to potential signatures in collider experiments, such as missing energy signals with specific kinematic features. Additionally, the presence of a hidden sector could have implications for other observables, such as the muon anomalous magnetic moment or rare decays of SM particles.
Experimental Distinctions:
Distinguishing these scenarios from the light DM scenario would require a multi-pronged approach:

Precision Higgs Measurements: Precise measurements of the Higgs boson's couplings to other SM particles can constrain the possibility of new decay channels and provide indirect evidence for exotic particles.
Direct and Indirect Searches: Dedicated experiments searching for direct and indirect signals of DM, ALPs, and other exotic particles are crucial for identifying the true nature of the invisible Higgs decay products.
Cosmological Observations: Measurements of the cosmic microwave background radiation and the large-scale structure of the universe can provide complementary constraints on the properties of DM and other exotic particles.

If light dark matter interacts with the Standard Model primarily through the Higgs portal, what are the implications for the formation of large-scale structures in the universe and the evolution of galaxies?

If light dark matter (DM) interacts with the Standard Model primarily through the Higgs portal, it would be weakly interacting and have a small scattering cross-section with baryonic matter. This has significant implications for the formation of large-scale structures and the evolution of galaxies:
1. Suppression of Small-Scale Structures:

Free Streaming: Light DM particles would have a larger free-streaming length compared to heavier, weakly interacting DM candidates. This means they could travel larger distances before becoming gravitationally bound, leading to a suppression of structure formation on small scales.
Impact on Halo Profiles: The suppression of small-scale structures would result in shallower DM halo profiles in galaxies. This is because the central regions of halos would receive less contribution from the suppressed small-scale fluctuations.
2. Warm Dark Matter Cosmology:

Warm vs. Cold Dark Matter: Light DM with a mass in the keV range is often referred to as "warm" dark matter, as opposed to "cold" dark matter, which is much heavier. Warm DM scenarios predict a different power spectrum of density fluctuations compared to cold DM, with a suppression of power on small scales.
Observational Consequences: This suppression of small-scale power could potentially alleviate some tensions between observations and the predictions of cold DM simulations, such as the "missing satellites" problem (the discrepancy between the observed number of dwarf galaxies and the larger number predicted by simulations) and the "core-cusp" problem (the discrepancy between the observed flat density profiles in the centers of some dwarf galaxies and the cuspy profiles predicted by simulations).
3. Impact on Galaxy Formation and Evolution:

Delayed Star Formation: The suppression of small-scale structures could lead to a delay in the formation of the first stars and galaxies, as the formation of these objects is thought to be seeded by the collapse of smaller DM halos.
Modified Galaxy Morphology: The shallower DM halo profiles predicted in warm DM scenarios could also affect the morphology and dynamics of galaxies. For example, it could lead to less concentrated stellar distributions and different rotation curves.
Observational Probes:
Several observational probes can be used to constrain the nature of light DM and its impact on structure formation:

Lyman-alpha Forest: The Lyman-alpha forest, which arises from the absorption of light from distant quasars by neutral hydrogen in the intergalactic medium, is a sensitive probe of the matter power spectrum on small scales.
Galaxy Luminosity Function: The distribution of galaxies as a function of their luminosity is sensitive to the underlying DM distribution and can be used to constrain the suppression of small-scale structures.
Gravitational Lensing: Gravitational lensing, the bending of light from distant sources by the gravitational field of intervening matter, can be used to map the distribution of DM in galaxies and clusters and constrain the shape of DM halos.
By combining these observational probes with theoretical modeling, we can gain a better understanding of the nature of DM and its role in the formation and evolution of the universe.