Yukawaon Approach to the Sumino Relation for Charged Lepton Masses

On the basis of a supersymmetric yukawaon model, Sumino's relation for charged lepton masses is re-derived. A relation between values of $K(\mu) \equiv (m_e +m_\mu + m_\tau)/(\sqrt{m_e} + \sqrt{m_\mu} + \sqrt{m_\tau})^2$ and $\kappa(\mu) \equiv \sqrt{m_e m_\mu m_\tau}/ (\sqrt{m_e} + \sqrt{m_\mu}+ \sqrt{m_\tau})^3$ is investigated without using a relation $K=2/3$. Predicted value of $\kappa(\mu)$ is compared with the observed value of $\kappa(\mu)$, and it is concluded that the value $\xi(\mu)\equiv (3/2)K(\mu) -1$ is of the order of $10^{-3}$ or less.Comment: 14 pages, 3 figures, version accepted by PL

New Trends in the Zee Model

Recent trends in the Zee model are reviewed. Especially, the importance of a serious constraint in the Zee model, sin^2 2\theta_{solar} =1.0, is pointed out.Comment: 3 pages, Latex, Plenary talk given at NuFact'01 (held in Tukuba, Japan, 24-30 May 2001), to appear in the Proceeding

Another Formula for the Charged Lepton Masses

A charged lepton mass formula $(m_e +m_\mu + m_\tau)/(\sqrt{m_e}+\sqrt{m_\mu} + \sqrt{m_\tau})^2 =2/3$ is well-known. Since we can, in general, have two relations for three quantities, we may also expect another relation for the charged lepton masses. Then, the relation will be expressed by a form of $\sqrt{m_e m_\mu m_\tau}/(\sqrt{m_e}+\sqrt{m_\mu} + \sqrt{m_\tau})^3$. According to this conjecture, a scalar potential model is speculated.Comment: 5 pages, no figure; a typo in Eq.(7) correcte

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

Seesaw Mass Matrix Model of Quarks and Leptons with Flavor-Triplet Higgs Scalars

In a seesaw mass matrix model M_f = m_L M_F^{-1} m_R^\dagger with a universal structure of m_L \propto m_R, as the origin of m_L (m_R) for quarks and eptons, flavor-triplet Higgs scalars whose vacuum expectation values v_i are proportional to the square roots of the charged lepton masses m_{ei}, i.e. v_i \propto \sqrt{m_{ei}}, are assumed. Then, it is investigated whether such a model can explain the observed neutrino masses and mixings (and also quark masses and mixings) or not.Comment: version accepted by EPJ

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

A Unified Description of Quark and Lepton Mass Matrices in a Universal Seesaw Model

In the democratic universal seesaw model, the mass matrices are given by \bar{f}_L m_L F_R + \bar{F}_L m_R f_R + \bar{F}_L M_F F_R (f: quarks and leptons; F: hypothetical heavy fermions), m_L and m_R are universal for up- and down-fermions, and M_F has a structure ({\bf 1}+ b_f X) (b_f is a flavour-dependent parameter, and X is a democratic matrix). The model can successfully explain the quark masses and CKM mixing parameters in terms of the charged lepton masses by adjusting only one parameter, b_f. However, so far, the model has not been able to give the observed bimaximal mixing for the neutrino sector. In the present paper, we consider that M_F in the quark sectors are still "fully" democratic, while M_F in the lepton sectors are partially democratic. Then, the revised model can reasonably give a nearly bimaximal mixing without spoiling the previous success in the quark sectors.Comment: 7 pages, no figur