Neutrino Mass Models Research Articles

Extended scotogenic model of neutrino mass and proton decay

The current article presents an extension of the classical scotogenic neutrino mass paradigm, where the three issues in particle physics: dark matter, smallness of neutrino mass, and stability of the proton are interconnected. The scenario encompasses the neutrino mass as well as the proton decay as a consequence of an existence of the dark matter. The study successfully achieves the correlation between the naturally small neutrino masses and naturally long proton lifetime in the present paradigm. Furthermore, all relevant cosmological, collider, and flavor physics constraints are incorporated in the detailed analysis. The scotogenic fermionic dark matter with the mass in the range from 100 GeV to 10 TeV successfully satisfies all relevant constraints. The valid range of 2.51×10−5<λ<2×10−3 is obtained for the 2HDM λ coupling. We give a brief discussion, as well as outline some of the future prospects. Published by the American Physical Society 2024

Neutrino mass model and dark matter with Y = 0 inert triplet scalar

We study a one-loop induced neutrino mass model with an inert isospin triplet scalar field of Y=0 and heavier isospin doublet vector-like leptons and singlet Majorana right-handed fermions. In addition to the neutrino mass matrix, we explain sizable scale of muon anomalous magnetic dipole moment 10−9 by introducing a singly-charged boson S±. We show numerical analysis of neutrino oscillation, lepton flavor violations, Z boson decays, and demonstrate our allowed regions in cases of normal and inverted hierarchies. We find the sizable scale of muon anomalous magnetic dipole moment for both cases. Then, we move on to the discussion of dark matter candidates to satisfy the relic density where we have two candidates; fermionic dark matter and bosonic one. And, we classify four cases fermionic dark matter with normal and inverted hierarchies, bosonic one with normal and inverted hierarchies and search for each of the allowed points in the model.

Asymmetric self-interacting dark matter with a canonical seesaw model

We study the possibility of generating dark matter (DM) and baryon asymmetry of the Universe (BAU) simultaneously in an asymmetric DM framework, which also alleviates the small-scale structure issues of cold DM. While the thermal relic of such self-interacting DM remains underabundant due to efficient annihilation into light mediators, a nonzero asymmetry in the dark sector can lead to the survival of the required DM in the Universe. The existence of a light mediator leads to the required self-interactions of DM at small scales while keeping DM properties similar to cold DM at large scales. It also ensures that the symmetric DM component annihilates away, leaving the asymmetric part in the spirit of cogenesis. The particle physics implementation is done in canonical seesaw models of light neutrino mass, connecting it to the origin of DM and BAU. In particular, we consider type-I and type-III seesaw origin of neutrino mass for simplicity and minimality of the field content. We show that the desired self-interactions and relic of DM together with BAU while satisfying relevant constraints lead to strict limits on DM mass O(GeV)≲MDM≲460 GeV. In spite of being a high-scale seesaw, the models remain verifiable in different experiments, including direct and indirect DM searches as well as colliders. Published by the American Physical Society 2024

The Type-I Seesaw family

We provide a comprehensive analysis of the Type-I Seesaw family of neutrino mass models, including the conventional type-I seesaw and its low-scale variants, namely the linear and inverse seesaws. We establish that all these models essentially correspond to a particular form of the type-I seesaw in the context of explicit lepton number violation. We then focus into the more interesting scenario of spontaneous lepton number violation, systematically categorizing all inequivalent minimal models. Furthermore, we identify and flesh out specific models that feature a rich majoron phenomenology and discuss some scenarios which, despite having heavy mediators and being invisible in processes such as μ → eγ, predict sizable rates for decays including the majoron in the final state.

Addendum to: A seesaw model for large neutrino masses in concordance with cosmology

Addendum to: A seesaw model for large neutrino masses in concordance with cosmology

Probing lepton number violation and Majorana nature of neutrinos at the LHC

Observation of lepton number (L) violation by two units at colliders would provide evidence for the Majorana nature of neutrinos. We study signals of L-violation in the context of two popular models of neutrino masses, the type-II seesaw model and the Zee model, wherein small neutrino masses arise at the tree-level and one-loop level, respectively. We focus on L-violation signals at the LHC arising through the process pp → ℓ±ℓ′± + jets within these frameworks. We obtain sensitivity to L-violation in the type-II seesaw model for triplet scalar masses up to 700 GeV and in the Zee model for charged scalar masses up to 4.8 TeV at the high-luminosity LHC with an integrated luminosity of 3 ab−1.

Texture zeros realization in a three-loop radiative neutrino mass model from modular A4 symmetry

We derive verifiable two-zero textures in the framework of a three-loop induced neutrino mass model applying a modular A4 symmetry for the lepton sector. Interestingly, the neutrino mass structure is determined by assignments of the right-handed charged-lepton particles only. We show all the possible texture patterns and demonstrate their analytical and numerical analyses. Finally, we mention a possibility of detection for doubly-charged boson via colliders that decays into specific modes due to the flavor symmetry.

One-loop matching of the type-III seesaw model onto the Standard Model Effective Field Theory

In previous works [1, 2], we have performed the one-loop matching of both type-I and type-II seesaw models for neutrino masses onto the Standard Model Effective Field Theories (SMEFT). In the present paper, by matching the type-III seesaw model onto the SMEFT at the one-loop level, we complete this series of studies on the construction of low-energy effective field theories (EFTs) for the canonical seesaw models. After integrating out the heavy fermionic triplets in the type-III seesaw model via both functional and diagrammatic approaches, we find 33 dimension-six (dim-6) operators in the Warsaw basis and their Wilson coefficients, while the number of dim-6 operators is 31 (or 41) for the EFT of type-I (or type-II) seesaw model. Furthermore, we calculate the branching ratios of radiative decays of charged leptons in the EFT. Then, the relationship between the beta function of the quartic Higgs coupling λ in the full theory and that of λEFT in the EFT is clarified. Finally, we briefly discuss the phenomenological implications of three types of seesaw EFTs and propose working observables that are sensitive to the four-fermion operators, which could be used to distinguish among different seesaw models in collider experiments.

Gravitational waves from phase transitions and cosmic strings in neutrino mass models with multiple majorons

We explore the origin of Majorana masses within the majoron model and how this can lead to the generation of a distinguishable primordial stochastic background of gravitational waves. We first show how in the simplest majoron model only a contribution from cosmic string can be within the reach of planned experiments. We then consider extensions containing multiple complex scalars, demonstrating how in this case a spectrum comprising contributions from both a strong first order phase transition and cosmic strings can naturally emerge. We show that the interplay between multiple scalar fields can amplify the phase transition signal, potentially leading to double peaks over the wideband sloped spectrum from cosmic strings. We also underscore the possibility of observing such a gravitational wave background to provide insights into the reheating temperature of the universe. We conclude highlighting how the model can be naturally combined with scenarios addressing the origin of matter of the universe, where baryogenesis occurs via leptogenesis and a right-handed neutrino plays the role of dark matter.

Modeling neutrino-induced scale-dependent galaxy clustering for photometric galaxy surveys

The increasing statistical precision of photometric redshift surveys requires improved accuracy of theoretical predictions for large-scale structure observables to obtain unbiased cosmological constraints. In ΛCDM cosmologies, massive neutrinos stream freely at small cosmological scales, suppressing the small-scale power spectrum. In massive neutrino cosmologies, galaxy bias modeling needs to accurately relate the scale-dependent growth of the underlying matter field to observed galaxy clustering statistics. In this work, we implement a computationally efficient approximation of the neutrino-induced scale-dependent bias (NISDB). Through simulated likelihood analyses of Dark Energy Survey Year 3 (DESY3) and Legacy Survey of Space and Time Year 1 (LSSTY1) synthetic data that contain an appreciable NISDB, we examine the impact of linear galaxy bias and neutrino mass modeling choices on cosmological parameter inference. We find model misspecification of the NISDB approximation and neutrino mass models to decrease the constraining power of photometric galaxy surveys and cause parameter biases in the cosmological interpretation of future surveys. We quantify these biases and devise mitigation strategies.

Neutrino mixing phenomenology: A4 discrete flavor symmetry with type-I seesaw mechanism

We study a neutrino mass model with [Formula: see text] discrete flavor symmetry using a type-I seesaw mechanism. The inclusion of extra flavons in our model leads to deviations from the exact tribimaximal mixing pattern resulting in a nonzero [Formula: see text] consistent with the recent experimental results and a sum rule for light neutrino masses is also obtained. In this framework, a connection is established among the neutrino mixing angles-reactor mixing angle ([Formula: see text]), solar mixing angle ([Formula: see text]), and atmospheric mixing angle ([Formula: see text]). This model also allows us a prediction of Dirac CP-phase and Jarlskog parameter [Formula: see text]. The octant of the atmospheric mixing angle [Formula: see text] occupies the lower octant. Our model prefers Normal Hierarchy (NH) than Inverted Hierarchy (IH). We use the parameter space of our model of neutrino masses to study the neutrinoless double beta decay parameter [Formula: see text].

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We study the prospects of probing neutrino mass models at the newly proposed antimuon collider μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu $$\\end{document}TRISTAN, involving μ+e-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu ^+e^-$$\\end{document} scattering at s=346GeV\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sqrt{s}= 346~\ ext {GeV}$$\\end{document} and μ+μ+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu ^+\\mu ^+$$\\end{document} scattering at s=2TeV.\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sqrt{s}= 2~\ ext {TeV}.$$\\end{document} We show that μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu $$\\end{document}TRISTAN is uniquely sensitive to leptophilic neutral and doubly-charged scalars naturally occurring in various neutrino mass models, such as Zee, Zee–Babu, cocktail, and type-II seesaw models, over a wide range of mass and coupling values, well beyond the current experimental constraints. It also allows for the possibility to correlate the collider signals with neutrino mixing parameters and charged lepton flavor violating observables.

The majoron coupling to charged leptons

The particle spectrum of all Majorana neutrino mass models with spontaneous violation of global lepton number include a Goldstone boson, the so-called majoron. The presence of this massless pseudoscalar changes the phenomenology dramatically. In this work we derive general analytical expressions for the 1-loop coupling of the majoron to charged leptons. These can be applied to any model featuring a majoron that have a clear hierarchy of energy scales, required for an expansion in powers of the low-energy scale to be valid. We show how to use our general results by applying them to some example models, finding full agreement with previous results in several popular scenarios and deriving novel ones in other setups.

$\mu-e$ conversion in a model of electroweak scale right-handed neutrino mass

We perform a detailed analysis of the \(\mu-e\) conversion within an extended version of the standard model (SM) with mirror symmetry and low energy of the electroweak scale of the type I seesaw neutrino mass generation. After a brief introduction to the model, we derive the \(\mu-e\) conversing ratio at one-loop approximation, in which the running inside are W gauge boson or singly charged scalars accompanying with neutrinos, and neutral scalars with new leptons. We focus, mainly, on predictions of observable possibilities and constraints set on relevant couplings from the \(\mu-e\) conversion in nuclei.

Scotogenic models with a general lepton flavor dependent U(1) gauge symmetry

We discuss radiative neutrino mass models with a general lepton flavor dependent U(1) gauge symmetry. The scotogenic model is adopted for neutrino mass generation in which Z2 odd singlet fermions and an inert scalar doublet are introduced. A lepton flavor dependent local U(1) symmetry is applied to realize two-zero texture of a Majorana mass matrix of Z2 odd singlet fermions where we explore minimal construction choosing U(1) charges of the standard model fermions and singlet fermions. Then we investigate neutrino mass matrix and show some predictions for constructed models, and discuss some phenomenological implications.

Neutrino mass model in the context of Δ(54)⊗Z2 ⊗ Z3 ⊗ Z4 flavor symmetries with Inverse Seesaw mechanism

Our analysis involves enhancing the Δ(54) flavor symmetry model with Inverse Seesaw mechanism along with two SM Higgs through the incorporation of distinct flavons. Additionally, we introduce supplementary Z2⊗Z3⊗Z4 symmetries to eliminate any undesirable components within our investigation. The exact tri-bimaximal neutrino mixing pattern undergoes a deviation as a result of the incorporation of extra flavons, leading to the emergence of a non-zero reactor angle θ13 that aligns with the latest experimental findings. It was found that for our model the atmospheric oscillation parameter occupies the lower octant for normal hierarchy case. We also examine the parameter space of the model for normal hierarchy to explore the Dirac CP (δCP), Jarlskog invariant parameter (J) and the Neutrinoless double-beta decay parameter (mββ) and found it in agreement with the neutrino latest data. Hence our model may be testable in the future neutrino experiments.

Radiative neutrino masses and the Cohen-Kaplan-Nelson bound

Recently, an increasing interest in UV/IR mixing phenomena has drawn attention to the range of validity of standard quantum field theory. Here we explore the consequences of such a limited range of validity in the context of radiative models for neutrino mass generation. We adopt an argument first published by Cohen, Kaplan and Nelson that gravity implies both UV and IR cutoffs, apply it to the loop integrals describing radiative corrections, and demonstrate that this effect has significant consequences for the parameter space of radiative neutrino mass models.

Exploring models with modular symmetry in neutrino oscillation experiments

Our study aims to investigate the viability of neutrino mass models that arise from discrete non-Abelian modular symmetry groups, i.e., ΓN with (N = 1, 2, 3, . ) in the future neutrino experiments T2HK, DUNE, and JUNO. Modular symmetry reduces the usage of flavon fields compared to the conventional discrete flavor symmetry models. Theories based on modular symmetries predict the values of leptonic mixing parameters, and therefore, these models can be tested in future neutrino experiments. In this study, we consider three models based on the A4 modular symmetry, i.e., Model-A, B, and C such a way that they predict different values of the oscillation parameters but still allowed with respect to the current data. In the future, it is expected that T2HK, DUNE, and JUNO will measure the neutrino oscillation parameters very precisely, and therefore, some of these models can be excluded in the future by these experiments. We have estimated the prediction of these models numerically and then used them as input to scrutinize these models in the neutrino experiments. Assuming the future best-fit values of θ23 and δCP remain the same as the current one, our results show that at 5σ C.L, Model-A can be excluded by T2HK whereas Model-B can be excluded by both T2HK and DUNE. Model-C cannot be excluded by T2HK and DUNE at 5σ C.L. Further; our results show that JUNO alone can exclude Model-B at an extremely high confidence level if the future best-fit of θ12 remains at the current-one. We have also identified the region in the θ23 - δCP parameter space, for which Model-A cannot be separated from Model-B in T2HK and DUNE.

SMEFT goes dark: Dark Matter models for four-fermion operators

We study ultra-violet completions for d = 6 four-fermion operators in the standard model effective field theory (SMEFT), focusing on models that contain cold dark matter candidates. Via a diagrammatic method, we generate systematically lists of possible UV completions, with the aim of providing sets of models, which are complete under certain, well specified assumptions. Within these lists of models we rediscover many known DM models, as diverse as R-parity conserving supersymmetry or the scotogenic neutrino mass model. Our lists, however, also contain many new constructions, which have not been studied in the literature so far. We also briefly discuss how our DM models could be constrained by reinterpretations of LHC searches and the prospects for HL-LHC and future lepton colliders.

Search for doubly charged Higgs boson production in multi-lepton final states using 139 fb^{-1} of proton–proton collisions at sqrt{s} = 13 TeV with the ATLAS detector

A search for pair production of doubly charged Higgs bosons (H^{pm pm }), each decaying into a pair of prompt, isolated, and highly energetic leptons with the same electric charge, is presented. The search uses a proton–proton collision data sample at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of 139 fb^{-1} recorded by the ATLAS detector during Run 2 of the Large Hadron Collider (LHC). This analysis focuses on same-charge leptonic decays, H^{pm pm } !rightarrow ell ^{pm } ell ^{prime pm } where ell , ell ^prime !=!e, mu , tau , in two-, three-, and four-lepton channels, but only considers final states which include electrons or muons. No evidence of a signal is observed. Corresponding upper limits on the production cross-section of a doubly charged Higgs boson are derived, as a function of its mass m(H^{pm pm }), at 95% confidence level. Assuming that the branching ratios to each of the possible leptonic final states are equal, mathcal {B}(H^{pm pm } rightarrow e^pm e^pm ) = mathcal {B}(H^{pm pm } rightarrow e^pm mu ^pm ) = mathcal {B}(H^{pm pm } rightarrow mu ^pm mu ^pm ) = mathcal {B}(H^{pm pm } rightarrow e^pm tau ^pm ) = mathcal {B}(H^{pm pm } rightarrow mu ^pm tau ^pm ) = mathcal {B}(H^{pm pm } rightarrow tau ^pm tau ^pm ) = 1/6, the observed (expected) lower limit on the mass of a doubly charged Higgs boson is 1080 GeV (1065 GeV) within the left-right symmetric type-II seesaw model, which is the strongest limit to date produced by the ATLAS Collaboration. Additionally, this paper provides the first direct test of the Zee–Babu neutrino mass model at the LHC, yielding an observed (expected) lower limit of m(H^{pm pm }) = 900 GeV (880 GeV).