We review the application of non abelian discrete groups to the theory of neutrino masses and mixing, which is strongly suggested by the agreement of the Tri-Bimaximal mixing pattern with experiment. After summarizing the motivation and the formalism, we discuss specific models, based on A4, S4 and other finite groups, and their phenomenological implications, including lepton flavor violating processes, leptogenesis and the extension to quarks. In alternative to Tri-Bimaximal mixing the application of discrete flavor symmetries to quark-lepton complementarity and Bimaximal Mixing is also considered.
We investigate the options for imposing flavor symmetries on a minimal renormalizable non-supersymmetric $\mathrm{SU}(5)$ grand unified theory, without introducing additional flavor-related fields. Such symmetries reduce the number of free parameters in the model and therefore lead to more predictive models. We consider the Yukawa sector of the Lagrangian, and search for all possible flavor symmetries. As a result, we find 25 distinct realistic flavor symmetry cases, with $\mathbb{Z}_2$, $\mathbb{Z}_3$, $\mathbb{Z}_4$, and $\mathrm{U}(1)$ symmetries, and no non-Abelian cases.
For a large set of flavor symmetries, the lowest-dimensional baryon- or lepton-number violating operators in the Standard Model effective field theory (SMEFT) with flavor symmetry are of mass dimension 9. As a consequence, baryon- and lepton-number violating processes are further suppressed with the introduction of flavor symmetries, e.g., the allowed scale associated with proton decay is typically lowered to $10^5$ GeV, which is significantly lower than the GUT scale. To illustrate these features, we discuss Minimal Flavor Violation for the Standard Model augmented by sterile neutrinos.
Modular flavor symmetries provide us with a new, promising approach to the flavor problem. However, in their original formulation the kinetic terms of the standard model fields do not have a preferred form, thus introducing additional parameters, which limit the predictive power of this scheme. In this work, we introduce the scheme of quasi-eclectic flavor symmetries as a simple fix. These symmetries are the direct product of a modular and a traditional flavor symmetry, which are spontaneously broken to a diagonal modular flavor subgroup. This allows us to construct a version of Feruglio's mod…
This dissertation investigates the flavor mixing effects in supersymmetric models on electroweak precision observables, Higgs boson mass predictions, B-physics observables, quark flavor violating Higgs decays, lepton flavor violating charged lepton decays and lepton flavor violating Higgs decays. The flavor mixing effects are studied in model independent way i.e. by putting off-diagonal entries in the sfermion mass matrix by hand as well as in the minimal flavor violating constrained MSSM, where mixing can originate from CKM matrix in the case of squarks and from PMNS matrix in the case of sle…
The phenomenology of flavor mixing of heavy Majorana neutrinos is studied. The physical degrees of freedom, which propagate like free particles until they decay in the presence of flavor mixing, are identified by diagonalizing the resummed propagator. It is shown that they should be interpreted as quasiparticles which lose Majorana nature.
We investigate origins of predictive one-zero neutrino mass textures in a systematic way. Here we search Abelian continuous(discrete) global symmetries, and non-Abelian discrete symmetries, and show how to realize these neutrino masses. Then we propose a concrete model involving a dark matter candidate and an extra gauge boson, and show their phenomenologies.
We consider the effects of Planck scale on four flavour neutrino mixings. The gravational interaction at $M_{x}=M_{\rm planck}$, we find that for degenerate neurino mass order, the Planck scale effects changes the mixing angle $θ'_{23}$, $θ'_{12}$ values and $θ'_{13}$, $θ'_{14}$, $θ'_{34}$, $θ'_{24}$ are unchanged above the GUT scale. In this paper, we study neutrino mixing in four flavor above the GUT scale.
The renormalization of theories with flavor mixing is discussed, and it is shown that the physical unstable particles should be interpreted as quasiparticles which cannot be regarded as external states. Several popular beliefs on renormalization are disproved accordingly, and the limitations of physical renormalization schemes are discussed. In addition, the properties of unstable particles with flavor mixing such as decay widths are studied from scattering mediated by them.
We discuss neutrino mass and mixing models based on discrete flavor symmetries. These models can include a variety of new interactions and non-standard particles such as sterile neutrinos, scalar Higgs singlets and multiplets. We point at connections of the models with leptogenesis and dark matter and the ways to detect the corresponding non-standard particles at intensity and energy frontier experiments.
In this paper, we suggest a simple model which induces realistic flavor structure from mixing of flavored Higgs doublets. The idea is based on the decoupling limit. In a model with many Higgs doublets, the mass eigenstates of scalars are linear combinations of Higgs doublets. If the mass matrix of Higgs fields has only one massless mode, and if the linear combination has flavor dependence, the induced Yukawa coupling will have nontrivial flavor structure. We suggest a mass matrix of flavored Higgs fields in a $U(2)_{L} \times U(2)_{R}$ toy model. An advantage of this model is that all of the e…
轻子混合模式背后的离散对称性的证据进行了分析。概述了“对称建筑”方案。一般的特点和问题，这一计划的实现一致规范模型制定。关键问题包括味对称性破缺、混合与质量的联系、味电荷的{ \it ad hoc}规定、“缺失”表象、新粒子的存在、TBM混合的可能偶然性质。我们考虑了将轻子对称性推广到夸克扇区并使之与大统一相协调的各种方法。在这方面，夸克-轻子互补性可能是一个可行的替代方案。观测结果的对称性和未来的实验测试他们的存在进行了讨论。
Neutrino flavor mixing is explained within the recently proposed low-scale minimal linear seesaw model of neutrino mass generation, a variant of the standard linear seesaw led by a Dirac pair of extra sterile neutrinos which is odd under a discrete $Z_2$ symmetry and has a mass at or below the GeV scale. The tri-bimaximal mixing and its deviations are derived straightforwardly on the basis of the symmetry between $μ$ and $τ$ flavors, without introducing non-abelian discrete flavor symmetries in the first place.
