Can the SO(10) model with one 10 and 126 Higgs scalar give observed masses mixings of quarks leptons without any other additional scalars? Recently, at least for charged leptons, it has been demonstrated that this is possible. However, neutrinos, usually said parameters are determined from quark lepton cannot large neutrino mixings. This problem systematically investigated, concluded present data exclude two scalars although best fit values data.

In order to shed light on the important question whether neutrinos are Dirac of Majorana particles, double β decay is investigated within a general form weak interaction Hamiltonian. The systematic study made 0+ →J+ nuclear transitions for tow-neutrino and neutrinoless modes both in two-nucleon- N*-mechanism. It shown that mode, only →0+ transition two-nucleon mechanism allowed if there no right-handed interaction. When gives sizable contribution, role →2+ becomes as transition. comparison...

We present a massive Majorana neutrino model and see how it is constrained from the solar atmospheric deficit experiments. This incorporates seesaw mechanism Peccei-Quinn symmetry. Its consequence to neutrinoless double beta decay also discussed.

We propose a model that all quark and lepton mass matrices have the same zero texture. Namely, their (1,1), (1,3), (3,1) components are zeros. The classified into two types. Type I is consistent with experimental data in sector. For sector, if seesaw mechanism not used, type II allows large ${\ensuremath{\nu}}_{\ensuremath{\mu}}\ensuremath{-}{\ensuremath{\nu}}_{\ensuremath{\tau}}$ mixing angle. However, severe compatibility neutrino oscillation experiments forces us to use mechanism. If we...

Recent neutrino data have been favourable to a nearly bimaximal mixing, which suggests simple form of the mass matrix. Stimulated by this matrix form, possibility that all matrices quarks and leptons same as in neutrinos is investigated. The constrained discrete symmetry Z_3 permutation S_2. model, course, leads mixing for lepton sectors, while, quark it can lead reasonable values CKM masses.

The general property of the pseudo Dirac neutrino is examined, and its phenomenological aspects to β decay, ν-oscillations ββ decay are discussed. As realistic examples, two models based on SU(5) GUTS presented their predictions as above-mentioned processes

The phenomenological model that all quark and lepton mass matrices have the same zero texture, namely their (1,1), (1,3), (3,1) components are zeros, is discussed in context of SO(10) grand unified theories (GUTs). type I for quarks consistent with experimental data sector. For sector, fitting to neutrino oscillation experiments forces us use matrix charged leptons which slightly deviated from I. Given masses masses, includes 19 free parameters, whereas GUTs give 16 constrained equations....

We reconsider a universal mass matrix model which has seesaw-invariant structure with four-zero texture common to all quarks and leptons. The Cabibbo-Kobayashi-Maskawa (CKM) quark Maki-Nakagawa-Sakata (MNS) lepton mixing matrices of the are analyzed analytically. show that can be consistent experimental data neutrino oscillation mixings by tuning free parameters model. It is also shown predicts relatively large value for (1, 3) element MNS matrix,...

We reanalyze the mass matrix model of quarks and leptons that gives a unified description quark lepton matrices with same texture form. By investigating possible types assignment for texture's components this form, we find different up than down can lead to consistent values CKM mixing matrix. This finding overcomes weak point in previous analysis model. also obtain some relations among parameters, which are independent evolution effects.

In the ββ decay, there are in general three parameters: neutrino mass (mν) and two right-handed weak current parameters (λ η). It is shown how to distinguish their contributions experimentally. Two useful measurable quantities single electron kinetic energy spectrum angular correlation between emitted electrons. The numerical results given for 76Ge case.

We examine the constraints on Maki-Nakagawa-Sakata lepton mixing matrix from present and future experimental data of neutrino oscillation, tritium beta decay, neutrinoless double decay for Majorana neutrinos. show that small angle solutions solar problem are disfavored averaged mass $(〈{m}_{\ensuremath{\nu}}〉)$ (\ensuremath{\leqslant}0.01 eV) in inverse hierarchy scenario. This is case even normal scenario except a very restrictive value $(\overline{{m}_{\ensuremath{\nu}}})$ single decay....

A phenomenological approach for the universal mass matrix model with a broken flavor 2 <-> 3 symmetry is explored by introducing antisymmetric parts of matrices quarks and charged leptons . We present explicit texture components matrices, which are consistent all neutrino oscillation experiments quark mixing data. The have common structure leptons, while large lepton mixings small derived no fine tuning due to difference phase factors. predicts value, 2.4 x 10^{-3}, element square...

Taking account of possible CP violation, we discuss about the constraints on lepton mixing angles from neutrinoless double beta decay and neutrino oscillation for three flavour Majorana neutrinos. From CHORUS experiment, combined with data decay, show that large angle solution (\theta_{23}) is improbable if mass (m_3) third generation a candidate hot dark matters.

We propose a model in which all quark and lepton mass matrices originally have the same zero texture, namely, their (1,1), (1,3), (3,1) components are zeros. For neutrino matrix, we further impose symmetry between second third generations. Then matrix has maximal ${\ensuremath{\nu}}_{\ensuremath{\mu}}\ensuremath{-}{\ensuremath{\nu}}_{\ensuremath{\tau}}$ mixing. Our is consistent with oscillation experiments also experimental data sector. The can be well incorporated seesaw mechanism.

We examine the constraints on Maki-Nakagawa-Sakata (MNS) lepton mixing matrix from present and future experimental data of neutrino oscillation number violation processes. introduce a graphical representation $\mathrm{CP}$ phases which appear in processes such as neutrinoless double beta decay, ${\ensuremath{\mu}}^{\ensuremath{-}}\ensuremath{-}{e}^{+}$ conversion, K...

We reanalyze the mass matrix model of quarks and leptons that gives a unified description quark lepton matrices with same texture form. By investigating possible types assignment for components matrix, we find different neutrinos than charged can also lead to consistent values Maki-Nakagawa-Sakata-Pontecorv (MNSP) mixing matrix. predicted value element ${U}_{13}$ depends on assignment. A proper will be discriminated by future experimental data ${U}_{13}.$

We study the bridge between phenomenological mass matrix model and SO(10) GUT. Namely, we consider four-zero texture in framework of renormalizable GUT model. This unification gives more stringent constraints than case where only either is considered. However, can obtain good fitting by expanding minimal to include 120 addition 10 [Formula: see text] Yukawa coupling considering both type I II seesaw mechanisms.

We propose a mass matrix model that gives unified description of quark and lepton with the same texture form based on flavor 2 <-> 3 symmetry. The is in contrast conventional picture forms sector will take somewhat different structures from those sector. By investigating possible types assignment for masses, we find our matrices can lead to small CKM mixings which are consistent experimental values. also some phase-parameter-independent relations among mixing elements.

We analyze the lepton sector of a recently proposed nonsymmetric mass matrix model. Our model gives unified description quark and with same texture form based on an extended flavor $2\ensuremath{\leftrightarrow}3$ symmetry phase. By investigating possible types assignment for masses, we find that can lead to large mixings which are consistent experimental values. also predicts very small value, $1.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$, mixing element square...

Based on a supersymmetric Yukawaon model with O(3) family symmetry, possible forms of quark and lepton mixing matrices are systematically investigated under condition that the up-quark mass matrix form leads to observed nearly tribimaximal in sector. Although previous could not provide good fitting mixing, present can give reasonably only for but also by using different origin $CP$ violation from one model.