Prog.Theor.Phys. 97, 459 (1997)
Analytical Expressions of Masses and Mixings
in a Democratic Seesaw Mass Matrix Model
Yoshio Koide and Hideo Fusaoka
On the basis of a seesaw-type mass matrix model
$M_f\simeq m_L M_F^{-1} m_R$ for quarks and leptons $f$,
analytical expressions of the masses and mixings of the fermions
$f$ are investigated. Here, the matrices $m_L$ and $m_R$ are
common to all $f$ (up- and down-; quarks and leptons), and
the matrix $M_F$ characterizing the heavy fermion sector
has the form [(unit matrix)+ (democratic-type matrix)].
An application to the quark sectors is discussed.
Flavor-Changing Neutral Currents Induced by
the Democratic Seesaw Mass Matrix
Flavor-changing neutral currents (FCNC) are studied on the basis of a
``democratic seesaw" mass matrix model, which
yields a singular enhancement of the top-quark mass $m_t$
and can give reasonable quark masses and CKM matrix elements.
The most exciting aspect of the model is that the structure of the
$6 \times 6$ right-handed fermion mixing matrix in the up-quark sector,
$U^R_u$, shows an abnormal structure in contrast to that of $U^L_u$.
This causes characteristic effects on the right-handed FCNC concerned
with top quark. A single top-quark production at future
$e^+ e^-$ colliders, $e^+ + e^- \rightarrow Z_R \rightarrow t +
\overline{c}$ ($\overline{t}+c$), is discussed.
New Algorithm for Tensor Calculation in Field Theories
Tensor calculation of suffix-contraction is
carried out by a C-program. Tensors are represented graphically,
and the algorithm makes use of the topology of graphs.
Classical and quantum gravity, in the weak-field
perturbative approach, is a special interest.
Examples of the leading order calculation of
some general invariants such as $R_{\mu\nu\lambda\sigma}
R^{\mu\nu\lambda\sigma}$~
are given.
Application to Weyl anomaly calculation is commented.
Mod.Phys.Lett. A11, 2849 (1996)
Neutrino Mixing in a Democratic-Seesaw-Mass-Matrix Model
On the basis of a seesaw-type mass matrix model for quarks and leptons,
$M_f \simeq m_L M_F^{-1} m_R$, where $m_L\propto m_R$ are universal
for $f=u,d,\nu$ and $e$ (up-quark-, down-quark-, neutrino- and charged
lepton-sectors), and $M_F$ has a form [(unit matrix)+(democratic-type
matrix)], neutrino masses and mixings are investigated.
It is tried to understand a large $\nu_\mu$-$\nu_\tau$ mixing,
i.e., $\sin^2 2\theta_{23}\sim 1$, with
$m_{\nu 1} \ll m_{\nu 2} \sim m_{\nu 3}$, which has been suggested
by the atmospheric neutrino data.
Weak Field Expansion of Gravity and Graphical Representation
Shoichi ICHINOSE and Noriaki IKEDA
We introduce a graphical representation for a global SO(n) tensor
$\partial_\mu\partial_\nu h_{\alpha\beta}$, which generally appears
in the perturbative approach of gravity around the flat space:
$g_{\mu\nu}=\delta_{\mu\nu}+h_{\mu\nu}$. We systematically construct
global SO(n) invariants.
Independence and completeness of those invariants
are shown by taking examples of $\partial\partial h$-,
and $
(\partial\partial h)^2$- invariants. They are classified
graphically. Indices which characterize all independent invariants
(or graphs) are given.
We apply the results to general invariants
with dimension $(Mass)^4$~ and the Gauss-Bonnet identity in 4-dim gravity.
- US - 96 - 02 and AMU - 96 - 01
A Democratic Seesaw Quark Mass Matrix
Related to the Charged Lepton Masses
Yoshio Koide and Hideo Fusaoka
We investigate a seesaw type mass matrix
$M_f\simeq m_L M_F^{-1} m_R$ for quarks and leptons, $f$,
under the assumptions that
the matrices $m_L$ and $m_R$ have common structures
for the quarks and leptons,
and that the matrix $M_F$ characterizing the heavy fermion sector
has the form [(unit matrix)+ (democratic-type matrix)].
We obtain well-satisfied relations for quark masses and mixings
related to the charged lepton masses.