We propose a flavour theory in which the family symmetry results naturally from a six-dimensional orbifold compactification. "Diracness" of neutrinos is a consequence of the spacetime dimensionality, and the fact that right-handed neutrinos live in the bulk. Dark matter is incorporated in a scotogenic way, as a result of an auxiliary $\mathbb{Z}_3$ symmetry, and its stability is associated to the conservation of a "dark parity" symmetry. The model leads naturally to a "golden" quark-lepton mass relation.
The use of extra space-time dimensions provides a promising approach to the flavour problem. The chosen compactification of a 6-dimensional orbifold implies a remnant family symmetry $A_4$. This makes interesting predictions for quark and lepton masses, for neutrino oscillations and neutrinoless double beta decay, providing also a very good global description of all flavour observables. Due to an auxiliary $\mathbb{Z}_4$ symmetry, we implement a scotogenic Majorana neutrino mass generation mechanism with a viable WIMP dark matter candidate.
We have studied the scotogenic model proposed by Ernest Ma, which is an extension of the Standard Model by three singlet right-handed neutrinos and a scalar doublet. This model proposes that the light neutrinos acquire a non-zero mass at 1-loop level. In this work, the realisation of the scotogenic model is done by using discrete symmetries $A_{4}\times Z_{4}$ in which the non-zero $θ_{13}$ is produced by assuming a non-degeneracy in the loop factor. Considering different lepton flavor violating(LFV) processes such as $l_α\longrightarrow l_βγ$ and $l_α\longrightarrow 3l_β$, their impact on neu…
In this work, we have studied lepton flavor violating (LFV) decays of $Z$ gauge boson and Higgs boson ($H$) in the scotogenic model. We have computed branching ratios for the decays $Z\to\ell_α\ell_β$ and $H\to\ell_α\ell_β$ in this model. Here, $\ell_α$ and $\ell_β$ are different charged lepton fields. After fitting to the neutrino oscillation observables in the scotogenic model, we have found that the branching ratios for the LFV decays of $Z$ and $H$ can be as large as $\sim10^{-8}$ and $\sim10^{-3}$ respectively. However, after satisfying the constraints due to non-observation of $\ell_α\to…
We show that if the lepton flavor violating $μ\rightarrow e γ$ process is observed in the MEG II experiment, the initial density of primordial black holes (PBHs) can be constrained with the scotogenic dark matter. As a benchmark case, if the PBH evaporation occurs in the radiation dominated era, the initial density may be $2\times 10^{-17} \lesssim β\lesssim 3 \times 10^{-16}$ for $\mathcal{O}$ (TeV) scale dark sector in the scotogenic model where $β=ρ_{\rm PBH}/ρ_{\rm rad}$ is the ratio of the PBH density $ρ_{\rm PBH}$ to the radiation density $ρ_{\rm rad}$ at the time of PBH formation. As an…
If the leptoquarks proposed to account for the intriguing anomalies observed in the $B$-meson decays, $R_{D^{(\ast)}}$ and $R_{K^{(\ast)}}$, as well as in the anomalous magnetic moment of the muon, $(g-2)_μ$, can be embedded into the scotogenic Dirac neutrino model, all these flavor anomalies, together with the origin of neutrino masses and the nature of dark matter, would be potentially addressed in a unified picture. Among the minimal seesaw, one-loop, and two-loop realizations of the dimension-4 effective operator $\mathcal{L}_{4}$ for the Dirac neutrino masses, we show that plenty of diagr…
In this paper, we propose a viable approach to realise two texture-zeros in the scotogenic model with flavor dependent $U(1)_{B-2L_α-L_β}$ gauge symmetry. These models are extended by two right-handed singlets $N_{Ri}$ and two inert scalar doublets $η_{i}$, which are odd under the dark $Z_2$ symmetry. Among all the six constructed textures, texture $A_1$ and $A_2$ are the only two allowed by current experimental limits. Then choosing texture $A_1$ derived from $U(1)_{B-2L_e-L_τ}$, we perform a detail analysis on the corresponding phenomenology such as predictions of neutrino mixing parameters,…
The scotogenic model can simultaneously account for the presence of dark matter and the origin of neutrino masses. We assume that the flavor neutrino mass matrix has one zero element and Yukawa matrix elements are real in the scotogenic model. It turns out that only one pattern of the flavor neutrino mass matrix in the one-zero-texture scheme within the scotogenic model is viable with the observed neutrino oscillation data, the relic abundance of the dark matter, and the upper limit of the branching ratio of the $μ\rightarrow e γ$ process.
The scotogenic model is well known for accommodating small neutrino mass and dark matter. Here, we have realized the scotogenic model with the help of discrete flavor symmetry $A_{4}\otimes Z_{4}$. We have obtained three one zero textures of Yukawa coupling matrices from the model and have studied its impact on neutrino phenomenology and related aspects of cosmology. On the basis of $μ-τ$ symmetry, we have further discarded two structures of one zero texture Yukawa coupling matrix. We further analyze if the effective mass of active neutrinos obtained by the virtue of the Yukawa coupling matrix…
We propose a minimal extention of the Standard Model where neutrino masses are generated radiatively at one-loop level via Scotogenic scanario. The model is augmented with $A_4$ modular symmetry as a scotogenic and flavor symmetry. With minimal number of parameters, the model makes predictions for neutrino oscillation data, Majorana and Dirac phases, dark matter characteristics, and neutrinoless double beta decay.
We present a singly charged scalar extension of the Scotogenic model, ScotoZee, which resolves the recently reported deviations in $W$ boson mass as well as lepton $g-2$. The model admits a scalar or a fermionic dark matter while realizing naturally small radiative neutrino masses. The mass splitting of $\sim 100$ GeV, required by the shift in $W$ boson mass, among the inert doublets fields can be evaded by its mixing with the singlet scalar, which is also key to resolving $(g-2)_\ell$ anomaly within $1σ$. We establish the consistency of this framework with dark matter relic abundance while sa…
We construct a scotogenic Majorana neutrino mass model in a gauged $U(1)_X$ extension of the standard model, where the mass of the gauge boson and the unbroken gauge symmetry, which leads to a stable dark matter (DM), can be achieved through the Stueckelberg mechanism. It is found that the simplest version of the extended model consists of the two inert-Higgs doublets and one vector-like singlet fermion. In addition to the Majorana neutrino mass, we study the lepton flavor violation (LFV) processes, such as $\ell_i \to \ell_j γ$, $\ell_i \to 3 \ell_j$, $μ-e$ conversion rate in nucleus, and muo…
We propose a scotogenic model for generating neutrino masses through a three-loop seesaw. It is a minimally extended inert doublet model with a spontaneously broken global symmetry $U(1)'$ and a preserved $\mathbb{Z}_2$ symmetry. The three-loop suppression allows the new particles to have masses at the TeV scale without fine-tuning the Yukawa couplings. The model leads to a rich phenomenology while satisfying all the current constraints imposed by neutrinoless double-beta decay, charged-lepton flavor violation, and electroweak precision observables. The relatively large Yukawa couplings lead t…
FIMP dark matter in the scotogenic model at low-reheating temperatures
Institución Universitaria ITM（ITM大学）；Universidad de Antioquia UdeA（安蒂奥基亚大学）；Universidade Federal do Rio Grande do Norte（北里奥格兰德联邦大学）；Millennium Institute for Subatomic Physics at High-Energy Frontier (SAPHIR)（高能前沿子物理千年研究所（SAPHIR））；Universidad de La Serena（拉塞雷纳大学）
In this paper, we propose a scotogenic model of neutrino masses with flavor-dependent $U(1)_{B-3L_α}(α=e, μ, τ)$ gauge symmetry, in which neutrinos are generated at one-loop level and a fermion dark matter is naturally accommodated. In this model, three one-zero-texture structures of neutrino mass matrix, denoted as patterns A, B and C, are successfully realized by appropriate charge assignment for inert fermions and scalar fields. For each predicted textures, a detailed numerical analysis is carried out to find the allowed regions of neutrino mixing and masses. We find three scenarios (A for …
We study the modular symmetry on magnetized toroidal orbifolds with Scherk-Schwarz phases. In particular, we investigate finite modular flavor groups for three-generation modes on magnetized orbifolds. The three-generation modes can be the three-dimensional irreducible representations of covering groups and central extended groups of $Γ_N$ for $N=3,4,5,7,8,16$, that is, covering groups of $Δ(6(N/2)^2)$ for $N=$ even and central extensions of $PSL(2,\mathbb{Z}_{N})$ for $N=$odd with Scherk-Schwarz phases. We also study anomaly behaviors.
Discovering a selection principle and the origin of flavor symmetries from an ultraviolet completion of particle physics is an interesting open task. As a step in this direction, we classify all possible flavor symmetries of 4D massless spectra emerging from supersymmetric Abelian orbifold compactifications, including roto-translations and non-factorizable compact spaces, for generic moduli values. Although these symmetries are valid in all string theories, we focus on the E8 x E8 heterotic string. We perform the widest known search of E8 x E8 Abelian orbifold compactifications, yielding over …
We suggest a common origin for dark matter, neutrino mass and family symmetry within the orbifold theory proposed in [arXiv:1910.05605v2,arXiv:2004.06735v2]. Flavor physics is described by an $A_4$ family symmetry that results naturally from compactification. WIMP Dark matter emerges from the first Kaluza-Klein excitation of the same scalar that drives family symmetry breaking and neutrino masses through the inverse seesaw mechanism. In addition to the "golden" quark-lepton mass relation and neutrino predictions for $0νββ$ decay, the model provides a good global description of all flavor obser…
Modular symmetries naturally combine with traditional flavor symmetries and $\mathcal{CP}$, giving rise to the so-called eclectic flavor symmetry. We apply this scheme to the two-dimensional $\mathbb{Z}_2$ orbifold, which is equipped with two modular symmetries $\mathrm{SL}(2,\mathbb{Z})_T$ and $\mathrm{SL}(2,\mathbb{Z})_U$ associated with two moduli: the Kähler modulus $T$ and the complex structure modulus $U$. The resulting finite modular group is $((S_3\times S_3)\rtimes \mathbb{Z}_4)\times\mathbb{Z}_2$ including mirror symmetry (that exchanges $T$ and $U$) and a generalized $\mathcal{CP}$-…
We address the possibility of realizing successful leptogenesis from dark matter annihilations in the scotogenic model of neutrino masses to explain the same order of magnitude abundance of dark matter and baryons in the present Universe. After showing that the minimal model in this category cannot satisfy all these requirements, we study a minimal extension of this model and find that the scale of leptogenesis can be as low as 5 TeV, lower than the one in vanilla leptogenesis scenario in scotogenic model along with the additional advantage of explaining the baryon-dark matter coincidence. Due…
The Scotogenic model is an economical scenario that generates neutrino masses at the 1-loop level and includes a dark matter candidate. This is achieved by means of an ad-hoc $\mathbb{Z}_2$ symmetry, which forbids the tree-level generation of neutrino masses and stabilizes the lightest $\mathbb{Z}_2$-odd state. Neutrino masses are also suppressed by a quartic coupling, usually denoted by $λ_5$. While the smallness of this parameter is natural, it is not explained in the context of the Scotogenic model. We construct an ultraviolet completion of the Scotogenic model that provides a natural expla…
We present a detailed analysis of the eclectic flavor structure of the two-dimensional $\mathbb Z_2$ orbifold with its two unconstrained moduli $T$ and $U$ as well as $\mathrm{SL}(2,\mathbb Z)_T\times \mathrm{SL}(2,\mathbb Z)_U$ modular symmetry. This provides a thorough understanding of mirror symmetry as well as the $R$-symmetries that appear as a consequence of the automorphy factors of modular transformations. It leads to a complete picture of local flavor unification in the $(T,U)$ modulus landscape. In view of applications towards the flavor structure of particle physics models, we are l…
We perform a complete analysis of the consistency of the singlet-triplet scotogenic model, where both dark matter and neutrino masses can be explained. We determine the parameter space that yields the proper thermal relic density been in agreement with neutrino physics, lepton flavor violation, direct and indirect dark matter searches. In particular, we calculate the dark matter annihilation into two photons, finding that the corresponding cross-section is below the present bounds reported by the Fermi-LAT and H.E.S.S. collaborations. We also determine the spin-dependent cross-section for dark…
We study quark and lepton mass matrices derived from magnetized $T^2/\mathbb{Z}_2$ orbifold models. Quark and lepton masses have a large hierarchy. In addition, mixing angles are large in the lepton sector, while those are small in the quark sector. We find that this structure can be realized in certain flavor models, which are identified by the zero points of the zero-mode wave functions of fermions and Higgs modes. We classify such realistic flavor models. Fixed points $τ=i$, $e^{2πi/3}$ and $i\infty$ of the modulus $τ$ play a role in realizing a large mass hierarchy through our scenario, wh…
We construct a scotogenic neutrino mass model introducing large $SU(2)_L$ multiplet fields without adding an extra symmetry. We have introduced extra scalar fields such as a septet, quintet and quartet where we make the vacuum expectation value of quartet scalar to be zero while septet and quintet develop non-zero ones. Then the neutrino mass is generated at one-loop level by introducing quintet fermion. We analyze the neutrino mass matrix taking constraints from lepton flavor violation into account and discuss collider physics regarding charged fermions from large multiplet fields. We have an…
Non-zero neutrino mass and dark matter cast a shadow over the success of the Standard Model (SM) of Particle Physics. The most straightforward extension of the SM to explain these two phenomena is the Scotogenic model, where the SM particle spectrum extends with three isospin singlet right-handed neutrinos and one doublet scalar while all of these being odd under $Z_2$ symmetry. In this work, we have considered the lightest right-handed neutrino as the dark matter candidate and freeze-out mechanism for producing observed dark matter relic density. The observed dark matter relic density, neutri…
We discuss the flavor structure in a resolutions of magnetized $T^2/\mathbb{Z}_2$ orbifold models. The flavor structure of Yukawa couplings among chiral zero-modes is sensitive to radii of the resolved fixed points of $T^2/\mathbb{Z}_2$ orbifold. We show in concrete models that the realistic mass hierarchy and mixing angles of the quark sector can be realized at certain values of blow-up radii, where the number of parameters in the blow-up model can be smaller than toroidal orbifold one.
The Scotogenic model is a popular scenario that induces radiative Majorana neutrino masses and includes a weakly-interacting dark matter candidate. We classify all possible ultraviolet extensions of the Scotogenic model in which (i) the dark $\mathbb{Z}_2$ parity emerges at low energies after the spontaneous breaking of a global $\rm U(1)_L$ lepton number symmetry, and (ii) the low-energy effective theory contains a naturally small lepton number breaking parameter, suppressed by the mass of a heavy mediator integrated out at tree-level. We find $50$ such models and discuss two of them in detai…
As the effective field theory of the superstring theory, ten-dimensional ${\cal N}=1$ supersymmetric Yang-Mills theory is induced. We consider the ten-dimensional space-time ${\cal M}_{10}$ as direct products of our four-dimensional space-time ${\cal M}_{4}$ and three two-dimensional compact spaces $X_i\ (i=1,2,3)$, i.e. ${\cal M}_{10} = {\cal M}_4 \times X_2 \times X_2 \times X_3$. In particular, we consider $X_i$ as a torus, the torus orbifold, and also the blow-up manifold of the torus orbifold with background magnetic fluxes. We discuss the modular symmetry in the magnetized torus and its …
As the first topic, we propose a new parametrization of the complex Yukawa matrix in the scotogenic model. The new parametrization is compatible with the particle data group parametrization of the neutrino sector. Some analytical expressions for the neutrino masses with the new parametrization are shown. As the second topic, we consider the phenomenology of the socotogenic model with the one-zero-textures of the neutrino flavor mass matrix. One of the six patterns of the neutrino mass matrix is favorable for the real Yukawa matrix. On the other hand, for the complex Yukawa matrix, five of the …
We construct the one-loop and two-loop scotogenic models for Dirac neutrino mass generation in the context of $U(1)_{B-L}$ extensions of standard model. It is indicated that the total number of intermediate fermion singlets is uniquely fixed by anomaly free condition and the new particles may have exotic $B-L$ charges so that the direct SM Yukawa mass term $\barν_Lν_R\overline{ϕ^0}$ and the Majorana mass term $(m_N/2)\overline{ν_R^C}ν_R$ are naturally forbidden. After the spontaneous breaking of $U(1)_{B-L}$ symmetry, the discrete $Z_{2}$ or $Z_{3}$ symmetry appears as the residual symmetry an…
