Hiroyuki Nishiura

Lepton and quark mass matrices

We propose a model that all quark and lepton mass matrices have the same zero texture. Namely their (1,1), (1,3) and (3,1) components are zeros. The mass matrices are classified into two types I and II. Type I is consistent with the experimental data in quark sector. For lepton sector, if seesaw mechanism is not used, Type II allows a large

Universal texture of quark and lepton mass matrices and a discrete symmetry Z 3

\nu_\mu - \nu_\tau

SO(10) GUT and quark-lepton mass matrices

mixing angle. However, severe compatibility with all neutrino oscillation experiments forces us to use the seesaw mechanism. If we adopt the seesaw mechanism, it turns out that Type I instead of II can be consistent with experimental data in the lepton sector too.

MNS parameters from neutrino oscillations, single beta decay and double beta decay

Recent neutrino data have been favorable to a nearly bimaximal mixing, which suggests a simple form of the neutrino mass matrix. Stimulated by this matrix form, the possibility that all the mass matrices of quarks and leptons have the same form as in neutrinos is investigated. The mass matrix form is constrained by a discrete symmetry

Broken flavor 2 3 symmetry and phenomenological approach for universal quark and lepton mass matrices

{\mathrm{Z}}_{3}

Phenomenological analysis of lepton and quark mass matrices

and a permutation symmetry

CP Violation in Neutrinoless Double Beta Decay and Neutrino Oscillation

{\mathrm{S}}_{2}.

Lepton mixing matrix element U(13) and new assignments of universal texture for quark and lepton mass matrices

The model, of course, leads to a nearly bimaximal mixing for the lepton sectors, while, for the quark sectors, it can lead to reasonable values of the CKM mixing matrix and masses.

Assignments of universal texture components for quark and lepton mass matrices

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

Graphical representation of CP violation effects in neutrinoless double beta decay

We examine the constraints on the MNS lepton mixing matrix =66rom the present and future experimental data of the neutrino oscillation, tritium beta decay, and neutrinoless double beta decay for Majorana neutrinos. We show that the small mixing angle solutions for solar neutrino problem are disfavored for small averaged mass (