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Cyclic symmetry in the neutrino sector with the type-I seesaw mechanism in the mass basis of charged leptons and right chiral neutrinos ($N_{iR}$, $i=e,\mu,\tau$) generates two fold degenerate light neutrino and three fold degenerate heavy…

High Energy Physics - Phenomenology · Physics 2016-06-08 Biswajit Adhikary , Mainak Chakraborty , Ambar Ghosal

We discuss effects of Majorana CP violation in a model-independent way for a given phase structure of flavor neutrino masses. To be more predictive, we confine ourselves to models with $\det(M_\nu)=0$, where $M_\nu$ is a flavor neutrino…

High Energy Physics - Phenomenology · Physics 2015-03-13 Teppei Baba , Masaki Yasue

An attempt is made to explore the possibility for deviations of solar mixing angle ($\theta_{12}$) from tri-bimaximal mixings, without sacrificing the predictions of maximal atmospheric mixing angle ($\theta_{23}=\pi/4$) and zero reactor…

High Energy Physics - Phenomenology · Physics 2008-11-26 N. Nimai Singh , Monisa Rajkhowa , Abhijit Borah

Implication of neutrino mass model based on $\Delta$(27) discrete flavor symmetry, on parameters of neutrino oscillations, CP violation and effective neutrino masses is studied using type-I seesaw mechanism. The Standard Model particle…

High Energy Physics - Phenomenology · Physics 2023-12-19 Ph. Wilina , N. Nimai Singh

We develop a class of left-right symmetric theories based on the gauge group $SU(3)_c \times SU(2)_L \times SU(2)_R \times U(1)$ with a generalized seesaw mechanism for generating the charged fermion masses. Neutrinos are naturally Dirac…

High Energy Physics - Phenomenology · Physics 2022-09-07 K. S. Babu , Xiao-Gang He , Mingxian Su , Anil Thapa

I review the interpretation of solar and atmospheric neutrino data in terms neutrino oscillations and describe some ways to account for the required neutrino masses and mixing angles from first principles, both within top-down and bottom-up…

High Energy Physics - Phenomenology · Physics 2009-09-17 J. W. F. Valle

Given the Dirac neutrino mass term, we explore the constraint conditions which allow the corresponding mass matrix to be invariant under the \mu-\tau reflection transformation, leading us to the phenomenologically favored predictions…

High Energy Physics - Phenomenology · Physics 2018-01-17 Zhi-zhong Xing , Di Zhang , Jing-yu Zhu

We propose a 3-3-1 model with neutral fermions based on $A_4$ flavor symmetry responsible for fermion masses and mixings with non-zero $\theta_{13}$. To get realistic neutrino mixing, we just add a new $SU(3)_L$ triplet being in…

High Energy Physics - Phenomenology · Physics 2015-08-03 V. V. Vien , H. N. Long

The discrete non-Abelian symmetry $A_4$, valid at some high-energy scale, naturally leads to degenerate neutrino masses, without spoiling the hierarchy of charged-lepton masses. Realistic neutrino mass splittings and mixing angles (one of…

High Energy Physics - Phenomenology · Physics 2009-09-17 K. S. Babu , Ernest Ma , J. W. F. Valle

The three Standard Model neutrinos can have Majorana mass or strictly Dirac mass, but both scenarios are practically indistinguishable in neutrino oscillation experiments. If they are pseudo-Dirac, however, there will be new mass splittings…

High Energy Physics - Phenomenology · Physics 2025-09-29 Chee Sheng Fong , Yago Porto

Assuming a minimal seesaw model with two heavy neutrinos (N), we examine effects of leptonic CP violation induced by approximate mu-tau symmetric interactions. As long as N is subject to the mu-tau symmetry, we can choose CP phases of Dirac…

High Energy Physics - Phenomenology · Physics 2008-11-26 Teppei Baba , Masaki Yasue

We have investigated a flavour model [1] which inspired by small squared-mass difference measured in solar neutrino oscillation experiments and observability in neutrinoless double beta decay experiments. In our model, the $1^{\rm st.}$ and…

High Energy Physics - Phenomenology · Physics 2017-08-23 Hiroyuki Ishida

We revisit a two right-handed neutrino model with two texture zeros, namely an indirect model based on A4 with the recently proposed new type of constrained sequential dominance (CSD2), involving vacuum alignments along the (0,1,-1)^T and…

High Energy Physics - Phenomenology · Physics 2013-06-04 Stefan Antusch , Stephen F. King , Martin Spinrath

We perform a comprehensive study of family symmetry models based on $A_4$ combined with the generalised CP symmetry $H_{\rm{CP}}$. We investigate the lepton mixing parameters which can be obtained from the original symmetry $A_4\rtimes…

High Energy Physics - Phenomenology · Physics 2015-06-16 Gui-Jun Ding , Stephen F. King , Alexander J. Stuart

We propose a complex extension of mixed $\mu\tau$ antisymmetry in the neutrino Majorana mass matrix $M_\nu$. This can be implemented in the Lagrangian by a generalized CP transformation (labeled by a mixing parameter $\theta$) on the…

High Energy Physics - Phenomenology · Physics 2019-02-27 Roopam Sinha , Probir Roy , Ambar Ghosal

We highlight in a model independent way the dependence of the effective Majorana mass parameter, relevant for neutrinoless double beta decay, on the CP phases of the PMNS matrix, using the most recent neutrino data including the…

High Energy Physics - Phenomenology · Physics 2009-11-10 Asmaa Abada , Gautam Bhattacharyya

Neutrino masses and mixings are analyzed in terms of left-handed fields and a 6x6 complex symmetric mass matrix whose singular values are the neutrino masses. An angle x_nu characterizes the kind of the neutrinos, with x_nu = 0 for Dirac…

High Energy Physics - Phenomenology · Physics 2007-05-23 Kevin Cahill

The 3-3-1 model proposed in 2011 based on discrete symmetry $S_4$ responsible for the neutrino and quark masses is updated, in which the non-zero $\theta_{13}$ is focused. Neutrino masses and mixings are consistent with the most recent data…

High Energy Physics - Phenomenology · Physics 2015-06-22 Vo Van Vien , Hoang Ngoc Long , Dinh Phan Khoi

We discuss the precision determination of the leptonic Dirac CP phase $\delta_{CP}$ in neutrino oscillation experiments, where we apply the concept of ``CP coverage''. We demonstrate that this approach carries more information than a…

High Energy Physics - Phenomenology · Physics 2014-11-18 Patrick Huber , Manfred Lindner , Walter Winter

We propose that leptonic CP violation arises from a breaking of the mu-tau exchange symmetry in the neutrino mass matrix which in turn is indicated by the near maximal atmospheric neutrino mixing and the near zero \theta_{13}. We find that…

High Energy Physics - Phenomenology · Physics 2008-11-26 R. N. Mohapatra , W. Rodejohann