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We construct lepton flavour models based on two $A_4$ modular symmetries. The two $A_4$ are broken by a bi-triplet field to the diagonal $A_4$ subgroup, resulting in an effective modular $A_4$ flavour symmetry with two moduli. We employ…

High Energy Physics - Phenomenology · Physics 2022-06-15 Ivo de Medeiros Varzielas , João Lourenço

In the modular symmetry approach to neutrino models, the flavour symmetry emerges as a finite subgroup $\Gamma_N$ of the modular symmetry, broken by the vacuum expectation value (VEV) of a modulus field $\tau$. If the VEV of the modulus…

High Energy Physics - Phenomenology · Physics 2026-01-13 Gui-Jun Ding , Stephen F. King , Xiang-Gan Liu , Jun-Nan Lu

Small discrete family symmetries such as S4, A4 or A5 may lead to simple leading-order predictions for the neutrino mixing matrix such as the bimaximal, tribimaximal or golden ratio mixing patterns, which may be brought into agreement with…

High Energy Physics - Phenomenology · Physics 2015-06-23 Peter Ballett , Stephen F. King , Christoph Luhn , Silvia Pascoli , Michael A. Schmidt

We construct two flavor models based on $S_4$ family symmetry and generalised CP symmetry. In both models, the $S_4$ family symmetry is broken down to the $Z^{SU}_2$ subgroup in the neutrino sector, as a consequence, the trimaximal…

High Energy Physics - Phenomenology · Physics 2014-02-19 Cai-Chang Li , Gui-Jun Ding

We construct a $D_4$ flavor model based on SU(3)_C X SU}(3_L X U(1)_X gauge symmetry responsible for fermion masses and mixings. The neutrinos get small masses from antisextets which are in a singlet and a doublet under $D_4$. If the D_4…

High Energy Physics - Phenomenology · Physics 2014-01-06 V. V. Vien , H. N. Long

Massive neutrinos and leptonic mixings have provided the first evidence of flavour violation in the lepton sector, opening a unique gateway to many new phenomena. Among the latter, one finds processes violating lepton number, charged lepton…

High Energy Physics - Phenomenology · Physics 2017-12-19 Ana M. Teixeira

The problem of neutrino masses and mixing angles is analysed in a class of supersymmetric grand unified models, with SO(10) gauge symmetry and global U(2) flavour symmetry. Adopting the seesaw mechanism for the generation of the neutrino…

High Energy Physics - Phenomenology · Physics 2009-10-30 G. Costa , E. Lunghi

The A_4 model of leptons was proposed originally for nearly degenerate neutrino masses. With minimal modification, it is shown to accommodate as well the cases of normal hierarchy and inverted hierarchy. In all cases, this new model…

High Energy Physics - Phenomenology · Physics 2009-11-10 Ernest Ma

We introduce a new texture for neutrino mixing named Tri-Permuting (TP) mixing matrix. This pattern is characterized by maximal solar and atmospheric angles and by a large reactor angle satisfying sin(theta_13)=1/3. The correct lepton…

High Energy Physics - Phenomenology · Physics 2015-03-19 F. Bazzocchi

Models based on flavor symmetries are the most often studied approaches to explain the unexpected structure of lepton mixing. In many flavor symmetry groups a product of two triplet representations contains a symmetric and an anti-symmetric…

High Energy Physics - Phenomenology · Physics 2013-04-04 Nina Memenga , Werner Rodejohann , He Zhang

We argue that the A_4 symmetry as required by three flavors of fermions may well-embed in the SU(3)_C X SU(3)_L X U(1)_X gauge model. The new neutral fermion singlets as introduced in a canonical seesaw mechanism can be combined with the…

High Energy Physics - Phenomenology · Physics 2015-03-13 P. V. Dong , L. T. Hue , H. N. Long , D. V. Soa

The recent measurements of the neutrino reactor angle require a re-examination of flavour models based on discrete groups. Indeed, when these models deal with the Tri-Bimaximal, the Bimaximal and the Golden Ratio mixing patterns, some…

High Energy Physics - Phenomenology · Physics 2022-03-02 Luca Merlo

Four different neutrino mass sum-rules have been analyzed: these frequently arise in flavor symmetry models based on the groups A_4, S_4 or T', which are often constructed to generate tri-bimaximal mixing. In general, neutrino mass can be…

High Energy Physics - Phenomenology · Physics 2011-07-22 James Barry , Werner Rodejohann

The Non-Abelian finite group PSL_2(7) is the only simple subgroup of SU(3) with a complex three-dimensional irreducible representation. It has two maximal subgroups, S_4 which, along with its own A_4 subgroup, has been successfully applied…

High Energy Physics - Phenomenology · Physics 2008-11-26 Christoph Luhn , Salah Nasri , Pierre Ramond

The search for possible mixing patterns of charged leptons and neutrinos is important to get clues of the origin of nearly maximal mixings, since there are some preferred bases of the lepton mass matrices given by underlying theories. We…

High Energy Physics - Phenomenology · Physics 2016-11-23 N. Haba , J. Sato , M. Tanimoto , K. Yoshioka

We look for predictive flavour patterns of the effective Majorana neutrino mass matrix that are compatible with current neutrino oscillation data. Our search is based on the assumption that the neutrino mass matrix contains equal elements…

High Energy Physics - Phenomenology · Physics 2016-04-20 Luis M. Cebola , David Emmanuel-Costa , Ricardo Gonzalez Felipe

The present article is an endeavor to look into some fruitful frameworks based on "Bi-maximal" neutrino mixing, from a model independent stand. The possibilities involving the correction or attenuation of the original BM mixing matrix,…

High Energy Physics - Phenomenology · Physics 2016-03-28 Subhankar Roy , N. Nimai Singh

We propose a model with radiatively induced neutrino mass at two-loop level, applying modular $A_4$ symmetry. The neutrino mass matrix is formulated where the structure of associated couplings are restricted by the symmetry. Then we show…

High Energy Physics - Phenomenology · Physics 2021-03-09 Takaaki Nomura , Hiroshi Okada

This is a review article about neutrino mass and mixing and flavour model building strategies based on discrete family symmetry. After a pedagogical introduction and overview of the whole of neutrino physics, we focus on the PMNS mixing…

High Energy Physics - Phenomenology · Physics 2016-03-01 Stephen F. King , Christoph Luhn

Assuming three light neutrinos and the see-saw mechanism we present a semiquantitative model of fermion masses based on (SUSY) SU(5) and abelian horizontal charges. A good description of the observed pattern of quark and lepton masses is…

High Energy Physics - Phenomenology · Physics 2008-11-26 Guido Altarelli , Ferruccio Feruglio