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We examine the possibility that the lepton mixing matrix may exhibit a strong form of mu-tau universality, in which corresponding elements of the mu- and tau-neutrino flavour eigenstates have equal moduli, and find that it is consistent…

High Energy Physics - Phenomenology · Physics 2009-11-07 P. F. Harrison , W. G. Scott

Recently a new mechanism has been proposed to cure the problem of fermion mass hierarchy in the Standard Model (SM) model. In this scenario, all SM charged fermions other than top quark arise from higher dimensional operators involving the…

High Energy Physics - Phenomenology · Physics 2013-05-30 Dilip Kumar Ghosh , R. S. Hundi

We study mixing of the Dirac neutrinos in the residual symmetries approach. The key difference from the Majorana case is that the Dirac mass matrix may have larger symmetries: $G_\nu=\mathbf{Z}_{n}$ with $n\geq3$. The symmetry group…

High Energy Physics - Phenomenology · Physics 2015-12-02 Arman Esmaili , Alexei Yu. Smirnov

We study quark and lepton mass matrices with the common modulus $\tau$ in the $A_4$ modular symmetry. The viable quark mass matrices are composed of modular forms of weights $2$, $4$ and $6$. It is remarked that the modulus $\tau$ is close…

High Energy Physics - Phenomenology · Physics 2020-05-05 Hiroshi Okada , Morimitsu Tanimoto

We analyze lepton asymmetry induced in the decay of right--handed neutrinos in a class of minimal left--right symmetric models. In these models, which assume low energy supersymmetry, the Dirac neutrino mass matrix is proportional to the…

High Energy Physics - Phenomenology · Physics 2015-06-25 K. S. Babu , A. Bachri , H. Aissaoui

Generally the diagonalization of the mass matrix of the charged leptons is a part of the neutrino UPMNS matrix. However, usually this contribution is ignored by assuming a diagonal mass matrix for charged leptons. In this letter we test…

High Energy Physics - Phenomenology · Physics 2015-06-03 Giovanna Cottin , Marco Aurelio Diaz , Benjamin Koch

We discuss the neutrino mass matrix based on the Occam's Razor approach in the framework of the seesaw mechanism. We impose four zeros in the Dirac neutrino mass matrix, which give the minimum number of parameters needed for the observed…

High Energy Physics - Phenomenology · Physics 2016-07-06 Yuya Kaneta , Yusuke Shimizu , Morimitsu Tanimoto , Tsutomu T. Yanagida

In an economical system with only two heavy right handed neutrinos, we postulate a new texture for $3 \times 2$ Dirac mass matrix $m_D$. This model implies one massless light neutrino and thus displays only two patterns of mass spectrum for…

High Energy Physics - Phenomenology · Physics 2008-11-26 Biswajoy Brahmachari , Nobuchika Okada

We propose a non-holomorphic modular $A_4$ model under the assumption of universal couplings. In this framework, a charged lepton mass hierarchy is not created through parameter fine tuning or hierarchical Yukawa couplings, but instead is…

High Energy Physics - Phenomenology · Physics 2026-04-20 Mohammed Abbas

We propose a predictive lepton model under a modular $S_4$ symmetry, where the neutrino mass matrix arises from a radiative seesaw at one-loop level. The tree-level mass matrix is forbidden by well-assigned modular weights, which also play…

High Energy Physics - Phenomenology · Physics 2021-12-15 Hiroshi Okada , Yuta Orikasa

We propose two new simple lepton flavor models in the framework of the $S_4$ flavor symmetry. The neutrino mass matrices, which are given by two complex parameters, lead to the inverted mass hierarchy. The charged lepton mass matrix has the…

High Energy Physics - Phenomenology · Physics 2016-01-27 Yusuke Shimizu , Morimitsu Tanimoto

We note that the emerging features of lepton mixing can be reproduced if, with inverted neutrino mass ordering, both the smallest neutrino mass and the $\tau\tau$ element of the neutrino mass matrix vanish. Then, the atmospheric neutrino…

High Energy Physics - Phenomenology · Physics 2015-06-16 Luís Lavoura , Werner Rodejohann , Atsushi Watanabe

In the extension of the Dimopoulos--Hall--Raby model of the fermion mass matrices to the neutrino sector, there is an entry in the up-quark and neutrino Dirac mass matrices which can be assumed to arise from the Yukawa coupling of a {\bf…

High Energy Physics - Phenomenology · Physics 2009-10-22 L. Lavoura , João P. Silva

The PMNS neutrino mixing matrix is given, in general, by the product of two unitary matrices associated with the diagonalization of the charged lepton and neutrino mass matrices, respectively. Assuming that the active flavor neutrinos…

High Energy Physics - Phenomenology · Physics 2008-11-26 S. T. Petcov , W. Rodejohann

Effects of the lightest neutrino mass in "flavoured" leptogenesis when the CP-violation necessary for the generation of the baryon asymmetry of the Universe is due exclusively to the Dirac and/or Majorana phases in the neutrino mixing…

High Energy Physics - Phenomenology · Physics 2009-07-22 E. Molinaro , S. T. Petcov , T. Shindou , Y. Takanishi

We speculate that the mass spectrum of three neutrinos might have a normal hierarchy as that of three charged leptons or that of three up-type (or down-type) quarks. In this spirit, we propose a novel parametrization of the $3\times 3$…

High Energy Physics - Phenomenology · Physics 2009-11-11 Harald Fritzsch , Zhi-zhong Xing

The Standard Model includes neutrinos as massless particles, but neutrino oscillations showed that neutrinos are not massless. A simple extension of adding gauge singlet fermions to the particle spectrum allows normal Yukawa mass terms for…

High Energy Physics - Phenomenology · Physics 2012-12-24 D. Jurciukonis , T. Gajdosik , A. Juodagalvis , T. Sabonis

Taking into account the latest neutrino oscillation data, we study texture zeros of the lepton mass matrices. Assuming the Dirac neutrino mass matrix M_D, the charged-lepton mass matrix M_l and the mass matrix of heavy right-handed Majorana…

High Energy Physics - Phenomenology · Physics 2013-02-01 Harald Fritzsch , Shun Zhou

We consider minimal modifications to tribimaximal (TBM) mixing matrix which accommodate non-zero mixing angle $\theta_{13}$ and CP violation. We derive four possible forms for the minimal modifications to TBM mixing in a model with $A_4$…

High Energy Physics - Phenomenology · Physics 2015-04-16 Sin Kyu Kang , Morimitsu Tanimoto

We reconsider an universal mass matrix model which has a seesaw-invariant structure with four-zero texture common to all quarks and leptons. The CKM quark and MNS lepton mixing matrices of the model are analyzed analytically.We show that…

High Energy Physics - Phenomenology · Physics 2014-11-18 Koichi Matsuda , Hiroyuki Nishiura