Permutation Symmetry S_3 and VEV Structure of Flavor-Triplet Higgs Scalars

A model with flavor-triplet Higgs scalars \phi_i (i=1,2,3)is investigated under a permutation symmetry S_3 and its symmetry breaking. A possible S_3 breaking form of the Higgs potential whose vacuum expectation values v_i=< \phi_i> satisfy a relation v_1^2 +v_2^2 +v_3^2 ={2/3}(v_1 +v_2 +v_3)^2 is investigated, because if we suppose a seesaw-like mass matrix model M_e = m M^{-1} m with m_{ij} \propto \delta_{ij} v_i and M_{ij} \propto \delta_{ij}, such a model can lead to the well-known charged lepton mass relation m_e +m_\mu +m_\tau = {2/3} (\sqrt{m_e}+\sqrt{m_\mu} +\sqrt{m_\tau})^2.Comment: 7 pages, 1 figure, final version to appear in PR

Charged Lepton Mass Formula -- Development and Prospect --

The recent devolopment on the charged lepton mass forumula m_e+m_{\mu}+m_{\tau}={2/3}(\sqrt{m_e}+\sqrt{m_\mu}+\sqrt{m_{\tau}})^2 is reviewed. An S_3 or A_4 model will be promising for the mass relation.Comment: Latex, 11 pages, no figure, Talk at Internationa Workshop on Neutrino Masses and Mixing, at Shizuoka, Japan, December, 17-19, 200

Yukawaon model and unified description of quark and lepton mass matrices

In the so-called yukawaon model, where effective Yukawa coupling constants Y_f^{eff} (f=e,\nu,u,d) are given by vacuum expectation values of gauge singlet scalars (yukawaons) Y_f with 3\times 3 flavor components, it is tried to give a unified description of quark and lepton mass matrices. Especially, without assuming any discrete symmetry in the lepton sector, nearly tribimaximal mixing is derived by assumed a simple up-quark mass matrix form.Comment: 4 pages, to appear in Proceedings of Lepton-Photon 200

Charged Lepton Mass Spectrum and a Scalar Potential Model

Stimulated by a recent work by Sumino, on the basis of a model in which effective Yukawa coupling constants are described by vacuum expectation values of a scalar $\Phi$ with $3\times 3$ components, a possible form of the scalar potential $V(\Phi)$ which can well describe the observed charged lepton mass spectrum is investigated without referring to a specific flavor symmetry model. A general relation among eigenvalues of is derived without referring to an explicit form of $V(\Phi)$.Comment: 9 pages, no figure, version to appear in Phys.Rev.

Neutrino Masses Without Seesaw Mechanism in a SUSY SU(5) Model With Additional 5ˉL′+5L′\bar{5}'_L+5'_L

A radiatively-induced neutrino mass matrix with a simple structure is proposed on the basis of an SU(5) SUSY GUT model with R-parity violation. The model has matter fields $\bar{5}'_{L}+5'_{L}$ in addition to the ordinary matter fields $\bar{5}_{L}+10_{L}$ and Higgs fields $H_u+\bar{H}_d$. The R-parity violating terms are given by $\bar{5}_{L} \bar{5}_{L} 10_{L}$, while the Yukawa interactions are given by $\bar{H}_d \bar{5}'_{L} 10_{L}$. Since the matter fields $\bar{5}'_L$ and $\bar{5}_L$ are different from each other at the unification scale, the R-parity violation effects at a low energy scale appear only through the $\bar{5}'_L \leftrightarrow \bar{5}_{L}$ mixings. In order to make this R-parity violation effect harmless for proton decay, a discrete symmetry Z_3 and a triplet-doublet splitting mechanism analogous to the Higgs sector are assumed.Comment: 4 pages, 1 figure, talk at ICHEP2004, to appear in Proceeding

Universal Seesaw Mass Matrix Model and SO(10)\times SO(10) Unification

On the universal seesaw mass matrix model, which is a promising model of the unified description of the quark and lepton mass matrices, the behaviors of the gauge coupling constants and intermediate energy scales in the SO(10)_L\times SO(10)_R model are investigated related to the neutrino mass generation scenarios. The unification of the gauge coupling constants in the framework of the non-SUSY model is possible if the SO(10) symmetry is broken via Pati-Salam type symmetries.Comment: Latex, 20 pages + one figur

Charged Lepton Mass Relations in a Supersymmetric Yukawaon Model

According to an idea that effective Yukawa coupling constants Y_f^{eff} are given vacuum expectation values of fields ("Yukawaons") Y_f as Y_f^{eff}=y_f /\Lambda, a possible superpotential form in the charged lepton sector under a U(3) [or O(3)] flavor symmetry is investigated. It is found that a specific form of the superpotential can lead to an empirical charged lepton mass relation without any adjustable parameters.Comment: 9 pages, no figure, final version to appear in Phys.Rev.