Trimaximal Mixing Research Articles

Phenomenological study of two minor zeros in neutrino mass matrix using trimaximal mixing

In this paper, we study the phenomenological implications of two minor zeros in neutrino mass matrix using trimaximal mixing matrix. In this context, we analyzed 15 possible cases of two minor zeros in neutrino mass matrix and found only two cases, namely, class [Formula: see text] and class [Formula: see text], that are compatible with the present neutrino oscillation data. We present correlations of several neutrino oscillation parameters and give prediction of the total neutrino mass, the values of effective Majorana mass, the effective electron anti-neutrino mass and CP violating Majorana phases for these two classes. We also explore the degree of fine tuning in the elements of neutrino mass matrix for the allowed classes. Moreover, we propose a flavor model within the seesaw model along with [Formula: see text] symmetry group that can generate such classes.

Neutrino mixing model for best-fit values of θ12 and θ13

Recently, the precise observations have yielded values for the neutrino mixing angles, denoted as [Formula: see text] and [Formula: see text]. Therefore, constructing a neutrino mixing model capable of accurately reflecting these measurements is crucial. In this paper, we propose a novel neutrino mixing model similar to the trimaximal mixing model. Unlike the trimaximal model that falls short of concurrently replicating the best-fit values of [Formula: see text] and [Formula: see text], our proposed mixing model has the ability to simultaneously reproduce the best-fit values for both angles.

Modified trimaximal mixing for solar and reactor neutrino mixing angles

The trimaximal mixing scheme is one of the widely studied neutrino mixing schemes. However, the predicted solar neutrino mixing angle [Formula: see text] and the reactor neutrino mixing angle [Formula: see text] cannot simultaneously realize their best-fit values. To address this issue, a minimal modification to the trimaximal mixing scheme is proposed. The modified trimaximal mixing scheme can simultaneously predict the best-fit values of [Formula: see text] and [Formula: see text] using an additional real parameter introduced via the modification.

New magic neutrino mass textures with three free parameters

Motivated by current experiments on searching for neutrinoless double beta decays, we study the phenomenological consequences and testability of the constraint relation “Mii=Mjj+Meμ+Meτ”, for i,j=e,μ,τ, on the magic neutrino mass matrix elements. This hypothesis is inspired by the μ−τ symmetry and gives rise to six different Majorana neutrino mass textures, including two textures one-zero. These obtained textures are diagonalized by the well-known trimaximal mixing which provides nonzero and nonmaximal reactor and atmospheric angles, respectively. Depending on the predominance of the e-row or μ-τ block, the preferred neutrino mass hierarchy and the lower limits on the |Mii| effective Majorana masses for each magic matrix are determined. Furthermore, in light of the global-fit results of neutrino oscillation parameters as reported by NuFIT 5.1, we also study the testability of these textures at the proposed neutrinoless double beta decay experiments such as KamLAND-Zen, GERDA Phase-II and nEXO, by incorporating the effective Majorana neutrino masses |Mij| that are generated through these neutrino mass matrices.

One vanishing minor in the neutrino mass matrix using trimaximal mixing

One vanishing minor in the neutrino mass matrix using trimaximal mixing

Trimaximal mixing and extended magic symmetry in a model of neutrino mass matrix

The trimaximal mixing scheme results in “magic” neutrino mass matrix which is known to accommodate neutrino oscillation data. In this paper, we propose a phenomenological ansatz for by extending the magic symmetry that leads to further reduction in the number of free parameters, thereby increasing the predictability of the model. The neutrino mixing parameters, effective Majorana mass m ee and CP invariants (J CP , I 1, I 2) are found to exhibit strong correlations for mixing paradigm. One of the generic feature of the model is the requirement of non-maximal for possible CP violation measurable in neutrino oscillation experiments. The observables m ee and sum of neutrino masses have imperative implications for yet unknown neutrino mass hierarchy. For inverted hierarchy, the lower bound on , predicted by the model, is found to be within the sensitivity reach of the decay experiments. Also, cosmological bound of 0.12 eV on , at 95% CL, refutes inverted hierarchy implying with normal hierarchy as the only viable possibility in the model. We have, also, illustrated a scenario wherein such a construction of the neutrino mass matrix can be realized using symmetry in the framework of Type-I+II seesaw mechanism.

Common origin of θ13 and dark matter within the flavor symmetric scoto-seesaw framework

To understand the observed pattern of neutrino masses and mixing as well as to account for the dark matter we propose a hybrid scoto-seesaw model based on the A4 discrete flavor symmetry. In this setup, including at least two heavy right-handed neutrinos is essential to employ the discrete flavor symmetry that mimics once popular tribimaximal neutrino mixing at the leading order via type-I seesaw. The scotogenic contribution then acts as a critical deviation to reproduce the observed value of the reactor mixing angle θ13 (within the trimaximal mixing scheme) and to accommodate potential dark matter candidates, pointing towards a common origin of θ13 and dark matter. The model predicts the atmospheric angle to be in the upper octant, excludes some regions on the Dirac CP phase, and restricts the Majorana phases too. Further, normal and inverted mass hierarchies can be distinguished for specific values of the relative phases associated with the complex light neutrino mass matrix. Owing to the considered flavor symmetry, contributions coming from the scotogenic mechanism towards the lepton flavor violating decays such as μ → eγ, τ → eγ vanish, and a lower limit on the second right-handed neutrino mass can be obtained. Prediction for the effective mass parameter appearing in the neutrinoless double beta decay falls within the sensitivity of future experiments such as LEGEND-1k and nEXO.

Phenomenology of Trimaximal Mixing with One Texture Equality

We study neutrino mass matrices with one texture equality and the neutrino mixing matrix having either its first ( T M 1 ) or second ( T M 2 ) column identical to that of the tribimaximal mixing matrix. We found that out of total fifteen possible neutrino mass matrices with one texture equality, only six textures are compatible with T M 1 mixing and six textures are compatible with T M 2 mixing in the light of the current neutrino oscillation data. These textures have interesting implications for the presently unknown parameters such as the neutrino mass scale, effective Majorana neutrino mass, effective neutrino mass, the atmospheric mixing, and the Dirac- and Majorana-type CP violating phases. We, also, present the S 3 group motivation for some of these textures.

Diagonal reflection symmetries, four-zero texture, and trimaximal mixing with predicted θ13 in an A4 symmetric model

Abstract In this paper, we impose a magic symmetry on the neutrino mass matrix mν with universal four-zero texture and diagonal reflection symmetries. Due to the magic symmetry, the Maki–Nakagawa–Sakata matrix inevitably has trimaximal mixing. Since the lepton sector has only six free parameters, the physical observables of leptons are all determined from the charged lepton masses mei, the neutrino mass differences $\Delta m_{i1}^{2}$, and the mixing angle θ23. This scheme predicts sin θ13 = 0.149, which is almost equal to the latest best fit, as a function of the lepton masses me, μ and the mass differences $\Delta m_{i1}^{2}$. Moreover, even if the mass matrix has perturbations that break the magic symmetry, the prediction of sin θ13 is retained with good accuracy for the four-zero texture with diagonal reflection symmetries.

Renormalization group evolution induced leptogenesis in the minimal seesaw model with the trimaximal mixing and mu-tau reflection symmetry

In this paper, we consider the imbedding of the popular and well-motivated trimaximal mixing and μ–τ reflection symmetry (which can help us shape the forms of the neutrino mass matrix) in the minimal seesaw model (which contains much fewer parameters than the general seesaw model) with two TeV-scale right-handed neutrinos (for realizing a low-scale seesaw) of nearly degenerate masses (for realizing a resonant leptogenesis). However, either for the trimaximal mixing scenario (which is realized through the Form Dominance approach here) or for the μ–τ reflection symmetry scenario, leptogenesis cannot proceed. To address this issue, we consider the possibility that the special forms of the neutrino mass matrix for the trimaximal mixing and μ–τ reflection symmetry are slightly broken by the renormalization group evolution effect, thus allowing leptogenesis to proceed. It is found that in the normal case of the neutrino mass ordering, the baryon asymmetry thus generated can reproduce the observed value. For completeness, we have also extended our analysis to the scenario that two right-handed neutrinos are not nearly degenerate any more. Unfortunately, in this scenario the final baryon asymmetry is smaller than the observed value by several orders of magnitude.

Leptogenesis, fermion masses and mixings in a SUSY SU(5) GUT with D4 flavor symmetry

We propose a model of fermion masses and mixings based on SU(5) grand unified theory (GUT) and a D4 flavor symmetry. This is a highly predictive 4D SU(5) GUT with a flavor symmetry that does not contain a triplet irreducible representation. The Yukawa matrices of quarks and charged leptons are obtained after integrating out heavy messenger fields from renormalizable superpotentials while neutrino masses are originated from the type I seesaw mechanism. The group theoretical factors from 24- and 45-dimensional Higgs fields lead to ratios between the Yukawa couplings in agreement with data, while the dangerous proton decay operators are highly suppressed. By performing a numerical fit, we find that the model captures accurately the mixing angles, the Yukawa couplings and the CP phase of the quark sector at the GUT scale. The neutrino masses are generated at the leading order with the prediction of trimaximal mixing while an additional effective operator is required to account for the baryon asymmetry of the universe (BAU). The model is remarkably predictive because only the normal neutrino mass ordering and the lower octant of the atmospheric angle are allowed while the CP conserving values of the Dirac neutrino phase δCP are excluded. Moreover, the predicted values of the effective Majorana mass mββ can be tested at future neutrinoless double beta decay experiments. An analytical and a numerical study of the BAU via the leptogenesis mechanism is performed. We focused on the regions of parameter space where leptogenesis from the lightest right-handed neutrino is successfully realized. Strong correlations between the parameters of the neutrino sector and the observed BAU are obtained.

Neutrino phenomenology in the flavored NMSSM without domain wall problems

We propose a next-to-minimal supersymmetric Standard Model (NMSSM) extended by an $\mathbb{A}_{4}\times \boldsymbol{Z}_{3}$ flavor symmetry and three right-handed neutrinos providing a detailed study of the neutrino sector and a solution to the domain wall problem. In this proposal, neutrino masses are generated through Type I seesaw mechanism while the mixing angles are described by the trimaximal mixing realized using the NMSSM singlet S and only two flavon fields. The phenomenology of neutrino parameters is studied for normal and inverted mass hierarchies. In particular, we numerically evaluated the observables related to neutrino masses and mixing, namely, $\sum m_{i}$, $m_{ee}$, $m_{\nu_{e}}$, and $\delta_{CP}$ where we find that the ranges of $m_{ee}$ and $m_{\nu_{e}}$ are accessible by current and future experiments while the obtained ranges of $\sum m_{i}$ and $\delta_{CP}$ lie within the current experimental data. Another attractive feature we discussed in this paper is the circumvention of the domain wall problem induced by the spontaneous breaking of the $\mathbb{A}_{4}\times \boldsymbol{Z}_{3}$ discrete symmetry. We first showed that the domain walls in the charged lepton sector occur at high energy scale leading to unproblematic domain walls, while in the neutrino sector they are inevitable. Then, to solve this problem, we reconsidered the well-known approach that relies on the explicit breaking of the discrete symmetry through the insertion of Planck-suppressed operators induced by supergravity. \keywords{Neutrino physics, Discrete flavor symmetry,Trimaximal mixing, Domain walls}

Trimaximal mixing with one texture zero of the inverse neutrino mass matrix

In this paper, we study the phenomenological implications of enforcing one texture zero on the inverse matrix of the neutrino mass matrix [Formula: see text] that can lead to the trimaximal mixing. It is found that the condition of [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] or [Formula: see text] can hold in the case of normal neutrino mass ordering, while the condition of [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] or [Formula: see text] can hold in the case of inverted neutrino mass ordering, where [Formula: see text] (for [Formula: see text], [Formula: see text]) denotes the [Formula: see text] entry of the inverse matrix of [Formula: see text]. The ranges of the absolute neutrino mass scale and three CP phases for these cases to hold are studied in some detail. The implications of these cases for the effective neutrino mass [Formula: see text] which controls the rates of the neutrino-less double beta decay processes are also given.

Phenomenology of two texture zero neutrino mass in left-right symmetric model with Z8 \xd7 Z2

We have done a phenomenological study on the neutrino mass matrix Mν favoring two zero texture in the framework of left-right symmetric model (LRSM) where type I and type II seesaw naturally occurs. The type I SS mass term is considered to be following a trimaximal mixing (TM) pattern. The symmetry realizations of these texture zero structures has been realized using the discrete cyclic abelian Z8 × Z2 group in LRSM. We have studied six of the popular texture zero classes named as A1, A2, B1, B2, B3 and B4 favoured by neutrino oscillation data in our analysis. We basically focused on the implications of these texture zero mass matrices in low energy phenomenon like neutrinoless double beta decay (NDBD) and lepton flavour violation (LFV) in LRSM scenario. For NDBD, we have considered only the dominant new physics contribution coming from the diagrams containing purely RH current and another from the charged Higgs scalar while ignoring the contributions coming from the left-right gauge boson mixing and heavy light neutrino mixing. The mass of the extra gauge bosons and scalars has been considered to be of the order of TeV scale which is accessible at the colliders.

Effective alignments as building blocks of flavor models

Flavour models typically rely on flavons - scalars that break the family symmetry by acquiring vacuum expectation values in specific directions. We develop the idea of effective alignments, i.e.\ cases where the contractions of multiple flavons give rise to directions that are hard or impossible to obtain directly by breaking the family symmetry. Focusing on the example where the symmetry is $S_4$, we list the effective alignments that can be obtained from flavons vacuum expectation values that arise naturally from $S_4$. Using those effective alignments as building blocks, it is possible to construct flavour models, for example by using the effective alignments in constrained sequential dominance models. We illustrate how to obtain several of the mixing schemes in the literature, and explicitly construct renormalizable models for three viable cases, two of which lead to trimaximal mixing scenarios.

Trimaximal mixing with a texture zero

We analyze neutrino mass matrices having one texture zero, assuming that the neutrino mixing matrix has either its first (TM$_1$) or second (TM$_2$) column identical to that of the tribimaximal mixing matrix. We found that all the six possible one texture zero neutrino mass matrices are compatible with the present neutrino oscillation data when combined with TM$_1$ or TM$_2$ mixing. These textures have interesting predictions for the presently unknown parameters such as the effective Majorana neutrino mass, the Dirac CP violating phase and the neutrino mass scale. We also present a way to theoretically realize some of these textures using $A_4$ symmetry within the framework of type-I+II seesaw mechanism.

Neutrino CP violation and sign of baryon asymmetry in the minimal seesaw model

We discuss the correlation between the CP violating Dirac phase of the lepton mixing matrix and the cosmological baryon asymmetry based on the leptogenesis in the minimal seesaw model with two right-handed Majorana neutrinos and the trimaximal mixing for neutrino flavors. The sign of the CP violating Dirac phase at low energy is fixed by the observed cosmological baryon asymmetry since there is only one phase parameter in the model. According to the recent T2K and NOνA data of the CP violation, the Dirac neutrino mass matrix of our model is fixed only for the normal hierarchy of neutrino masses.

Towards the minimal seesaw model via CP violation of neutrinos

We study the minimal seesaw model, where two right-handed Majorana neutrinos are introduced, focusing on the CP violating phase. In addition, we take the trimaximal mixing pattern for the neutrino flavor where the charged lepton mass matrix is diagonal. Owing to this symmetric framework, the 3 × 2 Dirac neutrino mass matrix is given in terms of a few parameters. It is found that the observation of the CP violating phase determines the flavor structure of the Dirac neutrino mass matrix in the minimal seesaw model. New minimal Dirac neutrino mass matrices are presented in the case of TM1, which is given by the additional 2-3 family mixing to the tri-bimaximal mixing basis in the normal hierarchy of neutrino masses. Our model includes the Littlest seesaw model by King et al. as one of the specific cases. Furthermore, it is remarked that our 3 × 2 Dirac neutrino mass matrix is reproduced by introducing gauge singlet flavons with the specific alignments of the VEV’s. These alignments are derived from the residual symmetry of S4 group.

Examination of pairs in neutrino mixing matrix

We exam the pairs of neutrino mixing matrix and suggest pairs that can be used in the construction of new mixing patterns, with "pair" denoting the equality of the modulus of a pair of matrix elements. The results show that the tri-maximal mixing in $\nu_2$ and the $\mu$-$\tau$ interchange symmetry are good choices under current experimental results. The two cases of bi-pair mixing pattern depend on the mass hierarchy of neutrinos. We also derive constraints on the CP-phase by the pairs. The results are compatible with the maximal CP-violation in most cases that are both self-consistent and consistent with experimental results.

Flavor structure in D-brane models: Majorana neutrino masses

We study the flavor structure in intersecting D-brane models. We study anomalies of the discrete flavor symmetries. We analyze the Majorana neutrino masses, which can be generated by D-brane instanton effects. It is found that a certain pattern of mass matrix is obtained and the cyclic permutation symmetry remains unbroken. As a result, trimaximal mixing matrix can be realized if Dirac neutrino mass and charged lepton mass matrices are diagonal.