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arXiv:0812.3203 [hep-ph] : December 17, 2008
International Journal of Modern Physics A, Vol.24 (2009) pp.3469-3475
DOI: 10.1142/S0217751X09047077
A talk given at ``Particle Physics, Astrophysics and Quantum Field
Theory: 75 Years since Solvay" (PAQFT08), 27-29 Nov. 2008,
Nanyang Executive Centre, Singapore.
Based on a new approach (the so-called Yukawaon model) to the mass
spectra and mixings, a neutrino mass matrix which is
described in terms of the up-quark masses and CKM matrix parameters
is proposed. The mass matrix successfully leads to a nearly
tribimaximal mixing without assuming any discrete symmetry.
Revised into OU-IHERP-09-01
arXiv:0811.3470 [hep-ph] : November 21, 2008
For the revised version, see (1) in 2009.
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 \langle Y_f\rangle of fields (``Yukawaons")
Y_f as Y_f^{eff}=y_f \langle Y_f\rangle/\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.
arXiv:0811.2839 [hep-ph] : November 18, 2008
For the revised version, see (3) in 2009.
Maximal CP Violation Hypothesis and a Lepton Mixing Matrix
Yoshio Koide and Hiroyuki Nishiura
Maximal CP violation hypothesis is applied to
a simple lepton mixing matrix form U=V_{CKM}^\dagger U_{TB},
which has recently been speculated under an ansatz that
U becomes an exact tribimaximal mixing U_{TB} in a limit
of the quark mixing matrix V_{CKM} \rightarrow {\bf 1}.
The prediction \tan^2 \theta_{12} =1/2 in the case of
the exact tribimaximal mixing U=U_{TB} is considerably
spoiled in the speculated mixing U=V_{CKM}^\dagger U_{TB}.
However, the application of the hypothesis
to the lepton sector can again recover
the spoiled value to \tan^2 \theta_{12} \simeq 1/2
if the original Kobayashi-Maskawa phase convention for
V_{CKM} is adopted.
arXiv:0809.2449 [hep-ph] : September 15, 2008
Physical Review D (2008) 093006-1 -- 8
DOI: 10.1103/PhysRevD.78.093006
Phenomenological Meaning of a Neutrino Mass Matrix
Related to Up-Quark Masses
Recently, a curious neutrino mass matrix has been proposed:
it is related to up-quark masses,
and it can excellently give a nearly tribimaxial mixing.
It is pointed out that, in order to obtain such successful
results, three phenomenological relations among masses and
CKM parameters must be simultaneously satisfied.
This suggests that there must be a specific flavor-basis
in which down-quark and charged lepton mass matrices are
simultaneously diagonalized.
arXiv:0808.0370 [hep-ph] : August 04, 2008
Physics Letters B 669 (2008) 24-27
DOI: 10.1016/j.physletb.2008.09.013
Testable Deviations from Exact Tribimaximal Mixing
Yoshio Koide and Hiroyuki Nishiura
A simple relation U_{MNS}=V_{CKM}^\dagger U_{TB}
between the lepton and quark mixing matrices (U_{MNS} and
V_{CKM}) is speculated under an ansatz that U_{MNS} becomes
an exact tribimaximal mixing U_{TB} in a limit V_{CKM}={\bf 1}.
By using the observed CKM mixing parameters, possible values
of neutrino oscillation parameters are estimated:
\sin^2 \theta_{13}=0.024-0.028, \sin^2 2\theta_{23}=0.94-0.95
and \tan^2 \theta_{12}=0.24-1.00 depending on phase conventions of
U_{TB}. Those values are testable soon by precision measurements
in neutrino oscillation experiments.
OU-IHERP-08-07 : July 09, 2008
arXiv:0807.3808 [hep-ph] : July 24, 2008
Physical Review D 78 (2008) 037302-1 -- 037302-3
DOI: 10.1103/PhysRevD.78.037302
Neutrino Mass Hierarchies in a Mass Matrix Form Versus its Inverse Form
A neutrino mass matrix model M_\nu with M_\nu^T =M_\nu
and a model with its inverse matrix form
\tilde{M}_\nu = m_0^2 (M_\nu^*)^{-1} can be diagonalized
by the same mixing matrix U_\nu.
It is investigated whether a scenario which provides a matrix
model M_\nu with normal mass hierarchy can also give a model
with an inverted mass hierarchy by considering a model with
an inverse form of M_\nu.
Revised version of arXiv:0804.4267 [hep-ph] : June 6, 2008
Physics Letters B 665 (2008) 227-230
DOI: 10.1016/j.physletb.2008.06.027
O(3) Flavor Symmetry and an Empirical Neutrino Mass Matrix
Based on a new approach to quark and lepton masses, where
the mass spectra originate in vacuum expectation values
of O(3)-flavor 1+5 (gauge singlet) scalars, a neutrino
mass matrix of a new type is speculated. The mass
matrix is described in terms of the up-quark
and charged lepton masses, and, by assuming a special flavor basis,
it can be accommodated to a nearly tribimaximal mixing without
explicitly assuming a discrete symmetry.
Quark mass relations are also discussed based on the
new approach.
arXiv:0804.4267 [hep-ph] : April 27, 2008
Nearly Tribimaximal Neutrino Mixing without Discrete Symmetry
Based on a new approach to quark and lepton masses, where
the mass spectra originate in vacuum expectation values
of U(3)-flavor nonet (gauge singlet) scalars, a neutrino
mass matrix of a new type is speculated. The mass
matrix is described in terms of the up-quark
and charged lepton masses, and it can lead to a nearly
tribimaximal mixing without assuming any discrete symmetry.
Quark mass relations are also discussed based on the
new approach.
arXiv:0803.3101 [hep-ph] : March 21, 2008
Jarnal of Physics G, 35 (2008) 125004-1 - 125004-11
DOI: 10.1088/0954-3899/35/12/125004
Empirical Neutrino Mass Matrix Related to Up-Quark Masses
Based on an approach to quark and lepton masses, where
the mass spectra originate in vacuum expectation values
of U(3) flavor nonet (gauge singlet) scalars, neutrino
masses and mixing are investigated. As an offshoot of
this approach, it is found that an empirical neutrino mass
matrix which is described in terms of the up-quark
and charged lepton masses can accommodate to a nearly
tribimaximal mixing.
arXiv:0802.1084 [hep-ph] : February 05, 2008
Physics Letters B662 (2008) 43 -- 48.
DOI:/10.1016/j.physletb.2008.02.059
U(3)-Flavor Nonet Scalar as an Origin of the Flavor Mass Spectra
According to an idea that the quark and lepton mass spectra
originate in a VEV structure of a U(3)-flavor nonet scalar \Phi,
the mass spectra of the down-quarks and charged leptons are
investigated. The U(3) flavor symmetry is spontaneously and
completely broken by non-zero and non-degenerated
VEVs of $\Phi$, without passing any subgroup of U(3).
The ratios (m_e+m_\mu+m_\tau)/(\sqrt{m_e}+\sqrt{m_\mu}+\sqrt{m_\tau})^2
and \sqrt{m_e m_\mu m_\tau}/(\sqrt{m_e}+\sqrt{m_\mu}+\sqrt{m_\tau})^3
are investigated based on a toy model.
arXiv: 0801.3491 [hep-ph]: January 23, 2008
Americal Institute of Physics, Conference Proceedings
Vol.1015 (2008), pp.80-86.
Invited talk given at International Workshop on Grand Unified
Theories: Current Status and Future Prospects, Ritsumeikan University,
Kusatsu, Shiga, Japan, December 17 - 19, 2007
How to Evade a No-Go Theorem in Flavor Symmetries
A no-go theorem in flavor symmetries is reviewed.
The theorem asserts that we cannot bring any flavor symmetry into
mass matrix model in which number of Higgs scalars is, at most,
one for each sector (e.g. H_u and H_d for up- and down-quark
sectors, respectively). Such the strong constraint comes from
the SU(2)_L symmetry. Possible three options to evade the
theorem are discussed.
arXiv:0801.3301 [hep-ph] : January 22, 2008
Journal of High Energy Physics, Vol.06, p.023 (2008)
F-term Induced Flavor Mass Spectrum
Naoyuki Haba and Yoshio Koide
New mechanism of generating flavor mass spectrum is proposed
by using an O'Raifeartaigh-type supersymmetry breaking model.
A desired bilinear form of fermion mass spectrum is naturally
realized through F-components of gauge-singlet (nonet of SU(3)
flavor symmetry) superfields, and the suitable charged-lepton
mass relation is reproduced. The charged-slepton mass spectrum
is non-degenerate in general, and can be even hierarchical
(proportional to the charged-lepton masses in the specific case).
Flavor changing neutral processes are suppressed since the
charged-lepton and slepton (except for right-handed sneutrino)
mass matrices are diagonalized simultaneously in the flavor space.
The right-handed {sneutrino}s are light with the similar ratio to
the lepton sector ($\tilde{m}_{\nu_R}$/$\tilde{m}_e \sim m_\nu$/$m_e$).
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