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We explore some important implications of the KamLAND measurment on the lepton flavor mixing matrix $V$ and the neutrino mass matrix $M$. The model-independent constraints on nine matrix elements of $V$ are obtained to a reasonable degree…
In the present work we study both thermal and non-thermal leptogenesis in all neutrino mass models describing the presently available neutrino mass patterns. We consider the Majorana CP violating phases coming from right-handed Majorana…
We discuss a simple model of lepton mixing and CP violation based on the flavor democracy of charge leptons and the mass degeneracy of neutrinos. A nearly bi-maximal flavor mixing pattern, which is favored by current data on atmospheric and…
We revisit the possibility of producing the observed baryon asymmetry of the Universe via thermal leptogenesis, where $CP$ violation comes exclusively from the low-energy phases of the neutrino mixing matrix. We demonstrate the viability of…
The seesaw extension of the SM explains the tiny neutrino masses and it is accompanied by many CP violating phases. We study the case where all leptonic CP violation arises from the soft breaking in the heavy Majorana mass matrix. Parameter…
The seesaw model of heavy and light Majorana neutrinos and its low-energy effective theory are studied, when the number of heavy neutrinos is equal to or less than the number of light lepton generations. We establish a general relationship…
We study the minimal extensions of the Standard Model by a linear combination of U(1)$_{L_e-L_\mu}$, U(1)$_{L_\mu-L_\tau}$ and U(1)$_{B-L}$ gauge symmetries, where three right-handed neutrinos and one U(1)-breaking SU(2)$_L$ singlet or…
Weak bases of flavors (u, c), (d,s), (e, \mu), (\nu_e,\nu_\mu) are assumed as the S_3 doublet and t, b, \tau, {\nu_\tau} are the S_3 singlet and further there are assumed S_3 doublet Higgs (H_1, H_2) and S_3 singlet Higgs H_S. We suggest an…
In the present paper, I have re-examined the weak basis invariants at low energies, proposed by C. Jarlskog and Branco et. al, respectively, in their earlier analyses, after confronting them with the assumptions of two zeros and an equality…
We examine minimal seesaw mechanism in which the masses of light neutrinos are described with tri/bi-maximal mixing in the basis where the charged-lepton Yukawa matrix and heavy Majorana neutrino mass matrix are diagonal. We search for all…
The effective Lagrangian for the seesaw model is derived including effects due to CP violation. Besides the usual dimension-5 operator responsible for light neutrino masses, a dimension-6 operator is obtained. For three or less heavy…
In models with flavour symmetries added to the gauge group of the Standard Model the CP-violating asymmetry necessary for leptogenesis may be related with low-energy parameters. A particular case of interest is when the flavour symmetry…
Extending the Standard Model with right-handed neutrinos provides a minimal explanation for both light neutrino masses (through the type-I seesaw mechanism) and the baryon asymmetry of our universe (through leptogenesis). We map here for…
Flavour models may display a relation between the CP-violating asymmetry for leptogenesis and low-energy parameters. If the flavour symmetry produces an exact mass independent lepton mixing scheme at leading order (with type I see-saw) the…
We discuss the minimal seesaw model for the Dirac CP violating phase of the lepton mixing matrix. We introduce two right-handed Majorana neutrinos and obtain several textures of the tri-maximal lepton mixing matrices. Moreover, we discuss…
The scaling hypothesis postulates proportionality of two columns of the Majorana neutrino mass matrix in the flavor basis. This Ansatz was shown to lead to an inverted hierarchy and U_{e3} = 0. We discuss theoretical and phenomenological…
CP violation in neutrino interactions is described by three phases contained in Pontecorvo-Maki-Nakagawa-Sakata mixing matrix ($U_{PMNS}$). We argue that the phenomenologocally consistent result of the Dirac CP violation can be obtained if…
Motivated by the fact that the Dirac phase in the PMNS matrix is the only CP-violating parameter in the leptonic sector that can be measured in neutrino oscillation experiments, we examine the possibility that it is the dominant source of…
We have shown that non-zero U_{e3} is generated in a see-saw type softly broken A_4 symmetric model through a single parameter perturbation in m_D in a single element. We have explored all possible 9 cases to study the neutrino mixing…
Neutrino mixing in the standard model extensions, both renormalizable and effective, with arbitrary numbers of the singlet and left-handed doublet neutrinos is investigated in a systematic fashion. The charged and neutral (the Z and Higgs…