2,288 research outputs found
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
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
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
S_4 Flavor Symmetry Embedded into SU(3) and Lepton Masses and Mixing
Based on an assumption that an S_4 flavor symmetry is embedded into SU(3), a
lepton mass matrix model is investigated. A Frogatt-Nielsen type model is
assumed, and the flavor structures of the masses and mixing are caused by VEVs
of SU(2)_L-singlet scalars \phi_u and \phi_d which are nonets (8+1) of the
SU(3) flavor symmetry, and which are broken into 2+3+3' and 1 of S_4. If we
require the invariance under the transformation (\phi^{(8)},\phi^{(1)}) \to
(-\phi^{(8)},+\phi^{(1)}) for the superpotential of the nonet field
\phi^{(8+1)}, the model leads to a beautiful relation for the charged lepton
masses. The observed tribimaximal neutrino mixing is understood by assuming two
SU(3) singlet right-handed neutrinos \nu_R^{(\pm)} and an SU(3) triplet scalar
\chi.Comment: 12 pages, no figure, to appear on JHE
A_4 Symmetry and Lepton Masses and Mixing
Stimulated by Ma's idea which explains the tribimaximal neutrino mixing by
assuming an A_4 flavor symmetry, a lepton mass matrix model is investigated. A
Frogatt-Nielsen type model is assumed, and the flavor structures of the masses
and mixing are caused by the VEVs of SU(2)_L-singlet scalars \phi_i^u and
\phi_i^d (i=1,2,3), which are assigned to {\bf 3} and ({\bf 1}, {\bf 1}',{\bf
1}'') of A_4, respectively.Comment: 13 pages including 1 table, errors in Sec.7 correcte
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
Quark Mass Matrix with a Structure of a Rank One Matrix Plus a Unit Matrix
A quark mass matrix model is proposed where
and is a
unit matrix plus a rank one matrix. Up- and down-quark mass matrices and
are described in terms of charged lepton masses and additional three
parameters (one in and two in ). The model can predict reasonable
quark mass ratios (not only , , and , but
also ) and Kobayashi-Maskawa matrix elements.Comment: 8 pages, Latex, no figure
Universal Seesaw Mass Matrix Model with an S_3 Symmetry
Stimulated by the phenomenological success of the universal seesaw mass
matrix model, where the mass terms for quarks and leptons f_i (i=1,2,3) and
hypothetical super-heavy fermions F_i are given by \bar{f}_L m_L F_R +\bar{F}_L
m_R f_R + \bar{F}_L M_F F_R + h.c. and the form of M_F is democratic on the
bases on which m_L and m_R are diagonal, the following model is discussed: The
mass terms M_F are invariant under the permutation symmetry S_3, and the mass
terms m_L and m_R are generated by breaking the S_3 symmetry spontaneously. The
model leads to an interesting relation for the charged lepton masses.Comment: 8 pages + 1 table, latex, no figures, references adde
Top Quark Mass Enhancement in a Seesaw-Type Quark Mass Matrix
We investigate the implications of a seesaw type mass matrix, i.e.,
, for quarks and leptons under the assumption
that the matrices and are common to all flavors (up-/down- and
quark-/lepton- sectors) and the matrices characterizing the heavy fermion
sectors have the form [(unit matrix) + (a democratic matrix)] where
is a flavor parameter. We find that by adjusting the complex parameter ,
the model can provide that while at the same time keeping without assuming any parameter with hierarchically different values
between and . The model with three adjustable parameters under the
``maximal" top quark mass enhancement can give reasonable values of five quark
mass ratios and four KM matrix parameters.Comment: 22 pages, Latex, 5 postscript figures available upon reques
Evolution of the Yukawa coupling constants and seesaw operators in the universal seesaw model
The general features of the evolution of the Yukawa coupling constants and
seesaw operators in the universal seesaw model with det M_F=0 are investigated.
Especially, it is checked whether the model causes bursts of Yukawa coupling
constants, because in the model not only the magnitude of the Yukawa coupling
constant (Y_L^u)_{33} in the up-quark sector but also that of (Y_L^d)_{33} in
the down-quark sector is of the order of one, i.e., (Y_L^u)_{33} \sim
(Y_L^d)_{33} \sim 1. The requirement that the model should be calculable
perturbatively puts some constraints on the values of the intermediate mass
scales and tan\beta (in the SUSY model).Comment: 21 pages, RevTex, 10 figure
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