Physical Review D69,093001 (2004)
Universal Texture of Quark and Lepton Mass Matrices
with an Extended Flavor 2\leftrightarrow 3 Symmetry
Against the conventional picture that the mass matrix forms
in the quark sectors will take somewhat different structures
from those in the lepton sectors, on the basis of an idea that
all the mass matrices of quarks and leptons have the same texture,
a universal texture of quark and lepton mass matrices is proposed
by assuming a discrete symmetry Z_3 and an extended flavor
2\leftrightarrow 3 symmetry. The texture is described by three
parameters (including phase parameter). According to this ansatz,
the neutrino masses and mixings are investigated.
Physics Letters, B574, 82-88 (2003)
Radiative Neutrino Masses in a SUSY GUT Model
Radiatively-induced neutrino mass matrix is investigated
within the framework of an SU(5) SUSY GUT model.
The model has matter fields of three families
\overline{5}_{L(+)i}+5_{L(+)i} in addition to the ordinary
matter fields $\overline{5}_{L(-)i}+10_{L(+)i}$ and
Higgs fields H_{(+)}+\overline{H}_{(0)},
where (+,0,-) denote the transformation properties
( \omega^{+1}, \omega^0, \omega^{-1}) (\omega^3=-1)
under a discrete symmetry Z_3.
R-parity violating terms are given by
\overline{5}_{L(+)} \overline{5}_{L(+)} 10_{L(+)},
while the Yukawa interactions are given by
\overline{H}_{(0)} \overline{5}_{L(-)} 10_{L(+)},
i.e. the \overline{5}-fields in both are different from
each other.
The Z_3 symmetry is only broken by the terms
\overline{5}_{L(+)i}5_{L(+)i} softly, so that the
\overline{5}_{L(+)i}\leftrightarrow \overline{5}_{L(-)i}
mixings appear at \mu < M_X.
Of the R-parity violating terms
\overline{5}_{L(+)} \overline{5}_{L(+)} 10_{L(+)},
only the terms (e_L\nu_-\nu_Le_)e_R^c sizably appear
at \mu < M_X.
Review of Administration and Informatics, Vo.16, No.1, 2003, p.1.
Extraordinary Solution in the Flood-Garber Model of Financial Crises
The Flood--Garber equation in a classical
model of financial crises has an extraordinary solution which
gives an exponential increase of the shadow exchange rate e_s(t).
In the Flood and Garber model, the shadow exchange rate e_s(t) is
assumed as a linear function in $t$, so that the collapse time t_c
can be predicted by using observed quantities at t< t_c.
However, such the assumption cannot be justified at all,
so that in general we cannot predict the collapse time t_c.
In the present paper, it is pointed out that this problem
originates in a more fundamental property of the differential equation:
a solution of an n-th order differential equation inevitably
contains n integration constants,
which are fixed only by boundary conditions (initial
conditions); since the behavior of e_s(t) is
unknown for t< t_c,
we cannot use boundary conditions at t< t_c, but
we can use only those at t \geq t_c; this means that
the boundary condition at t=t_c is incompetent to predict
the collapse time t_c.
Phys. Rev. D68, 056004 (2003).
R-Parity Violation in a SUSY GUT Model
and Radiative Neutrino Masses
Yoshio Koide and Joe Sato
Within the framework of an SU(5) SUSY GUT model, a mechanism
which effectively induces R-parity-violating terms below the
unification energy scale M_X is proposed. The model has matter
fields \overline{5}_{L(+)}+10_{L(-)} and Higgs fields
H_{(-)} and \overline{H}_{(+)} in addition to the ordinary
Higgs fields H_{(+)} and \overline{H}_{(-)} which contribute
to the Yukawa interactions, where (\pm) denote the transformation
properties under a discrete symmetry Z_2. The Z_2 symmetry is
only broken by the \mu-term \overline{H}_{(+)}H_{(-)} softly,
so that the \overline{5}_{(+)}\leftrightarrow \overline{H}_{(+)}
\leftrightarrow \overline{H}_{(-)} mixing appears at \mu < m_{SB},
i.e. R-parity violating terms \overline{5}_L\overline{5}_L 10_L
are effectively induced from the Yukawa interactions
\overline{H}_{(-)}\overline{5}_{L(+)} 10_{L(-)}, so that the
effective coupling constants \lambda_{ijk} of
\nu_{Li} e_{Lj} e_{Rk}^c and \nu_{Li} d_{Rj}^c d_{Lk}
are proportional to the mass matrices (M_e^*)_{jk} and
(M_d^\dagger)_{jk}, respectively. The parameter regions
which are harmless for the proton decay are investigated.
Possible forms of the radiatively induced neutrino mass matrix
are also investigated.
Talk at International Workshop on "Neutrino Oscillations
and their Origin" (NOON2003) (Feb. 2003)
To be published in Proceedings (World Scientific)
Universal Texture of
Quark and Lepton Mass Matrices
Yoshio Koide, Hiroyuki Nishiura, Koichi Matsuda, Tatsuru Kikuchi and
Takeshi Fukuyama
Against the conventional picture that the mass matrix forms in the
quark sectors will take somewhat different structures from those in the
lepton sectors, a possibility that all the mass
matrices of quarks and leptons have the same form as in the
neutrinos is investigated.
For the lepton sectors, the model leads to a nearly bimaximal mixing
with the prediction |U_{e3}|^2=m_e/2m_\mu=0.0024 and
\tan^2\theta_{sol} \simeq m_{\nu 1}/m_{\nu 2}, and so on.
For the quark sectors, it can lead to reasonable values of
the CKM mixing matrix and masses:
|V_{us}|\simeq \sqrt{m_d/m_s}, |V_{ub}|\simeq |V_{cb}|\sqrt{m_u/m_c},
|V_{td}| \simeq |V_{cb}|\cdot |V_{us}|, and so on.