Maximizing the Trilinear Higgs Coupling in a 3-3-1 Effective Field Theory Derived from a Specific 3-3-1 Model

Core Concepts

This paper explores the potential of a specific 3-3-1 model's effective field theory (EFT) to predict a significantly enhanced trilinear Higgs coupling, a key parameter for probing physics beyond the Standard Model, and analyzes the theoretical and experimental constraints on achieving this enhancement.

Abstract

Bibliographic Information

Cherchiglia, A., & Leite, L. J. F. (2024). Maximal value for trilinear Higgs coupling in a 3-3-1 EFT. arXiv preprint arXiv:2411.00094v1.

Research Objective

This paper investigates the maximal possible value of the trilinear Higgs coupling (λhhh) within a specific 3-3-1 effective field theory (EFT) framework, derived from a 3-3-1 model with a particular choice of scalar triplets and fermion representations. The authors aim to determine if this EFT can accommodate values of λhhh significantly larger than the Standard Model prediction, potentially detectable at future colliders like the HL-LHC.

Methodology

The authors first construct the 3-3-1 EFT by integrating out heavy degrees of freedom from the UV-complete 3-3-1 model at tree level. They then match the EFT to a Two-Higgs-Doublet Model (2HDM), identifying the relationships between the parameters of both models. Analytical formulas for λhhh, including one-loop corrections, are presented for both the general 2HDM and the specific 3-3-1 EFT. The authors then perform a numerical scan of the parameter space, considering theoretical constraints (stability, perturbativity, unitarity) as well as experimental bounds from electroweak precision observables, collider data, and flavor physics.

Key Findings

• The 3-3-1 EFT predicts a suppressed quartic coupling (Λ5) and naturally small Λ6,7 couplings in the 2HDM mapping, effectively reducing the number of free parameters compared to a general 2HDM.
• The maximum achievable value of λhhh in the 3-3-1 EFT is constrained by the perturbative unitarity bound, which limits the allowed mass splitting between the pseudoscalar Higgs (A) and other BSM scalars.
• While smaller than the maximal values found in general 2HDM studies, the 3-3-1 EFT can still accommodate a λhhh enhancement of more than four times the Standard Model prediction.
• Achieving such large enhancements requires considering scenarios with small deviations from the alignment limit (sin(β − α) = 1), a region not typically explored in the literature.

Main Conclusions

The 3-3-1 EFT studied in this paper provides a well-motivated framework that can accommodate a significantly enhanced trilinear Higgs coupling, potentially observable at future colliders. The authors emphasize the importance of exploring small deviations from the alignment limit, which can open up new regions of parameter space allowing for larger λhhh values.

Significance

This research contributes to the ongoing effort to identify and constrain BSM physics scenarios that could be probed through precision Higgs measurements. The study highlights the potential of specific 3-3-1 models and their EFTs to predict measurable deviations in the Higgs sector, providing valuable guidance for future experimental searches.

Limitations and Future Research

The analysis primarily focuses on one-loop corrections to λhhh. Including two-loop contributions, known to be significant in the alignment limit, could further refine the predicted maximal values and potentially reveal new allowed regions in the parameter space. Additionally, exploring the impact of different 3-3-1 model variations and fermion representations on the EFT predictions would be a valuable avenue for future research.

Stats

The Z′ mass in the 3-3-1 model has a lower bound around 4 TeV.
The trilinear Higgs coupling κλ is expected to be constrained to [0.5,1.6] at 68% confidence-level in the LHC high-luminosity (HL-LHC) phase.
Two-loop corrections to κλ in the 2HDM can be up to 60% larger than the one-loop corrections for some corners of the parameter space.
The bound sβ−α > 0.995 is enforced for type II 2HDM at 95% C.L.

Quotes

"In this work, we obtain a consistent EFT for a class of models based on the gauge group SU(3)c × SU(3)L × U(1)Y."
"By imposing bounds from electroweak precision observables, collider, flavor, as well as theoretical considerations we obtain that the maximum value of the trilinear Higgs coupling is more than four times larger than the SM prediction, potentially testable at the LHC Hi-Lumi upgrade and other future colliders."
"Moreover, we find that such large values are only attainable if one considers an out-of-alignment scenario, even if the deviation is very small, which is not typically considered in the literature."

Key Insights Distilled From

Maximal value for trilinear Higgs coupling in a 3-3-1 EFT

by Adriano Cher... at arxiv.org 11-04-2024

https://arxiv.org/pdf/2411.00094.pdf

Deeper Inquiries

How would the inclusion of higher-order corrections beyond one-loop impact the predicted maximal value of the trilinear Higgs coupling in this 3-3-1 EFT?

Answer:
Including higher-order corrections, particularly two-loop contributions, could significantly impact the predicted maximal value of the trilinear Higgs coupling (λhhh) in the 3-3-1 EFT. Here's why:

Magnitude of Two-Loop Effects: As the provided text mentions, studies in the alignment limit of the Two-Higgs-Doublet Model (2HDM) have shown that two-loop corrections to λhhh can be substantial, sometimes even exceeding the one-loop corrections [15]. While the exact magnitude is parameter-dependent, this highlights the potential importance of higher-order terms.
Non-Alignment Considerations: The authors of the text focused on a non-alignment scenario to explore a wider parameter space. Two-loop corrections for λhhh in the non-alignment case are currently unknown. Calculating these would be a complex undertaking but potentially crucial for accurate predictions.
Impact on Allowed Parameter Space: Two-loop corrections could reshape the allowed regions in the parameter space spanned by sβ−α, mA, mH, mH±, and tβ. This might either enhance or reduce the predicted maximal value of λhhh depending on the interplay of different contributions.
Theoretical Uncertainties: Relying solely on one-loop calculations introduces theoretical uncertainties. Including higher-order corrections helps reduce these uncertainties, leading to more robust predictions for the maximal enhancement of the trilinear Higgs coupling.
In summary, while computationally challenging, incorporating two-loop corrections is essential for a complete understanding of the maximum possible enhancement of λhhh in the 3-3-1 EFT. It could significantly influence the theoretical predictions and their comparison with future experimental results.

Could alternative new physics scenarios beyond the explored 3-3-1 model framework also accommodate a similarly enhanced trilinear Higgs coupling while satisfying current experimental constraints?

Answer:
Yes, alternative new physics scenarios beyond the 3-3-1 model framework could potentially accommodate an enhanced trilinear Higgs coupling while remaining consistent with current experimental constraints. Here are a few examples:

Extensions of the Higgs Sector: Models with additional Higgs doublets or singlets, beyond the two doublets in the 2HDM, can modify the Higgs self-interactions and lead to an enhanced λhhh. The specific enhancement would depend on the model's details, such as the number of additional scalars, their couplings to the SM Higgs, and the imposed symmetries.

Vector-like Fermions: Introducing new vector-like fermions that couple to the Higgs boson can also modify the running of the Higgs self-coupling, potentially leading to an enhancement at low energies. The magnitude of the effect would depend on the masses and couplings of these new fermions.

Supersymmetric Extensions: Some supersymmetric models, particularly those with extended Higgs sectors, can predict modifications to the Higgs trilinear coupling. The precise impact depends on the specific supersymmetry-breaking mechanism and the mass spectrum of the supersymmetric particles.

Composite Higgs Models: In composite Higgs models, the Higgs boson is not a fundamental scalar but rather a bound state of new strong dynamics. These models can predict deviations in the Higgs couplings, including a possible enhancement of λhhh, depending on the details of the compositeness scale and the couplings of the Higgs to the new strong sector.
It's important to note that any successful model aiming to enhance λhhh must simultaneously satisfy existing experimental constraints. These include:

Direct Searches: Constraints from direct searches for new particles at colliders like the LHC.
Electroweak Precision Observables: Agreement with precision measurements of electroweak parameters.
Flavor Physics: Constraints from flavor-changing neutral current processes, which are sensitive to new physics contributions.
Exploring these alternative new physics scenarios and their potential to accommodate an enhanced trilinear Higgs coupling while respecting experimental bounds is an active area of research in particle physics.

What are the broader implications for cosmology and early universe physics if future experiments confirm a significantly enhanced trilinear Higgs coupling as predicted by this EFT?

Answer:
Confirming a significantly enhanced trilinear Higgs coupling (λhhh) would have profound implications for our understanding of cosmology and early universe physics:

Electroweak Phase Transition: The strength of the electroweak phase transition (EWPT), a crucial event in the early universe where the electroweak symmetry was broken, is highly sensitive to the Higgs self-coupling. A larger λhhh could lead to a first-order EWPT, a key requirement for electroweak baryogenesis.

Baryogenesis: Explaining the observed matter-antimatter asymmetry in the universe is a fundamental challenge. Electroweak baryogenesis, a mechanism relying on a strong first-order EWPT, would be favored by an enhanced λhhh, potentially providing a solution to this puzzle.

Inflationary Dynamics: The Higgs field itself could have played a role in the inflationary epoch, a period of rapid expansion in the very early universe. Modifications to the Higgs potential, such as an enhanced λhhh, could alter the inflationary dynamics and leave observable imprints on the cosmic microwave background (CMB).

Beyond the Standard Model Physics: A confirmed enhancement of λhhh would be a clear indication of physics beyond the Standard Model (BSM). It would point towards new particles or interactions at energy scales potentially accessible at future colliders, opening up new avenues for exploring the fundamental constituents of matter.

Dark Matter Connections: Some BSM scenarios that modify the Higgs trilinear coupling also offer dark matter candidates. An enhanced λhhh could indirectly hint at the nature of dark matter and its connection to the Higgs sector.
In conclusion, experimental verification of a significantly enhanced trilinear Higgs coupling would be a groundbreaking discovery. It would not only revolutionize our understanding of the Higgs boson's properties but also provide crucial insights into the early universe's evolution, the origin of matter, and the nature of physics beyond the Standard Model.