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(7) MISC-2012-19: October 27, 2012
Revised version was published in JHEP 2013
Neutrino Mass Matrix Model with a Double Seesaw Form
Yoshio Koide and Hiroyukai Nishiura
Within the framework of the so-called yukawaon model, which has
been proposed for the purpose of a unified description of
the lepton mixing matrix $U_{PMNS}$
and the quark mixing matrix $V_{CKM}$,
a neutrino mass matrix model with a double seesaw form
$M_\nu = k_\nu (m_D M_R^{-1} m_D^T)^2$ is proposed.
The model has only two adjustable parameters for the PMNS mixing and
neutrino mass ratios.
(Other parameters are fixed from the observed quark and charged
lepton mass ratios and CKM mixing.)
The model can give reasonable values $\sin^2 2\theta_{12} \simeq 0.85$
and $\sin^2 2\theta_{23} \sim 1$ and $\sin^2 2\theta_{13} \sim 0.09$
together with $R_\nu \equiv \Delta m^2_{21}/\Delta m^2_{32} \sim 0.03$.
Our prediction of the effective neutrino mass $\langle m \rangle$
in the neutrinoless double beta decay takes a sizable value
$\langle m \rangle \simeq 0.0034$ eV.
(6) MISC-2012-17: September 06, 2012
arXiv:1209.1275 [hep-ph]: September 07, 2012
For revised version, see 2013 (1)
Large theta_{13}^\nu and Unified Description
of Quark and Lepton Mixing Matrices
Yoshio Koide and Hiroyukai Nishiura
We present a revised version of the so-called ``yukawaon model",
which was proposed
for the purpose of a unified description of the lepton mixing matrix
$U_{PMNS}$ and the quark mixing matrix $V_{CKM}$.
It is assumed from a phenomenological
point of view that the
neutrino Dirac mass matrix $M_D$ is given
with a somewhat different structure from the charged lepton
mass matrix $M_e$,
although $M_D=M_e$ was assumed in the previous model.
As a result, the revised model predicts a reasonable value
$\sin^2 2\theta_{13} \sim 0.07$ with keeping successful results for
other parameters in $U_{PMNS}$ as well as $V_{CKM}$ and quark
and lepton mass ratios.
(5) MISC-2012-18, August 25, 2012
arXiv:1209.1694 [hep-ph]: September 11, 2012
Title was changed: October 19, 2012
Publised in Physical Review D87, 016016 (2013)
For revised version, see 2013 (2).
Can Mass of the Lightest Family Gauge Boson be of the Order of TeV?
The observed sign of a deviation from the $e$-$\mu$ universality
in tau decays suggests family gauge bosons with
an inverted mass hierarchy.
Under the constraints from the observed $K^0$-$\bar{K}^0$ and
$D^0$-$\bar{D}^0$ mixing, we investigate a possibility
that a mass $M_{33}$ of the lightest gauge boson $A_3^3$ which
couples with only the third generation quarks and leptons is of
the order of TeV.
It is concluded that $M_{33} \sim 1$ TeV is possible if we
adopt a specific model phenomenologically.
arXiv:1207.2308 [hep-ph]: July 11, 2012
Invited talk presented by YK at GUT2012, March 15-17 (2012),
Kyoto, Japan
AIP Conf. Proc. 1467, pp. 15-20 (2012)
Family Gauge Bosons with an Inverted Mass Hierarchy
Yoshio Koide and Toshifumi Yamashita
A model that gives family gauge bosons with an inverted
mass hierarchy is proposed, stimulated by Sumino's cancellation
mechanism for the QED radiative correction to the charged
lepton masses.
The Sumino mechanism cannot straightforwardly be applied to SUSY
models because of the non-renormalization theorem.
In this talk, an alternative model which is applicable
to a SUSY model is proposed.
It is essential that family gauge boson masses $m(A_i^j)$
in this model is given by an inverted mass hierarchy
$m(A_i^i) \propto 1/\sqrt{m_{ei}}$, in contrast to
$m(A_i^i) \propto \sqrt{m_{ei}}$ in the original Sumino model.
Phenomenological meaning of the model is also investigated.
In particular, we notice a deviation from the $e$-$\mu$ universality in the
tau decays.
(3) OU-HET-741/2012; MISC-2012-05
arXiv:1203.2028 [hep-ph]: March. 09, 2012
Physics Letters B 711, pp. 384 - 398 (2012)
DOI:10.1016/j.physletb.2012.04.028
Family Gauge Bosons with an Inverted Mass Hierarchy
Yoshio Koide and Toshifumi Yamashita
A model that gives family gauge bosons with an inverted
mass hierarchy is proposed, stimulated by Sumino's cancellation
mechanism for the QED radiative correction to the charged
lepton masses.
The Sumino mechanism cannot straightforwardly be applied to SUSY
models because of the non-renormalization theorem.
In this paper, an alternative model which is applicable
to a SUSY model is proposed.
It is essential that family gauge boson masses $m(A_i^j)$
in this model is given by an inverted mass hierarchy
$m(A_i^i) \propto 1/\sqrt{m_{ei}}$, in contrast to
$m(A_i^i) \propto \sqrt{m_{ei}}$ in the original Sumino model.
Phenomenological meaning of the model is also investigated.
In particular, we notice a deviation from the e-\mu universality in the
tau decays.
(2) OU-HET-740/2012; MISC-2012-04
arXiv:1202.5815 [hep-ph]: Feb. 27, 2012
Physics Letters B 712, pp.396 - 400 (2012)
DOI: /10.1016/j.physletb.2012.05.014
Yukawaon model with U(3)$\times$S$_3$ family symmetries
Yoshio Koide and Hiroyukai Nishiura
A new yukawaon model is investigated under a family symmetry
U(3)$\times$S$_3$.
In this model, all vacuum expectation values (VEVs)
of the yukawaons, $\langle Y_f\rangle$, are described in terms of
a fundamental VEV matrix $\langle \Phi_0 \rangle$ as in the
previous yukawaon model, but the assignments of quantum number for fields
are different from the previous ones: the fundamental
yukawaon $\Phi_0$ is assigned to $(3,3)$ of U(3)$\times$U(3),
which is broken into $(3,1+2)$ of U(3)$\times$S$_3$, although quarks and
leptons are still assigned to triplets of U(3) and yukawaons
$Y_f$ are assigned to ${\bf 6}^*$ of U(3).
Then, VEV relations among Yukawaons become more concise considerably
than the previous yukawaon models.
By adjusting parameters, we can fit not only quark
mixing parameters but also lepton mixing parameters
together with their mass ratios.
(1) Revised version of (3) in 2011: OU-HET-711/2011; MISC-2011-11
arXiv:1106.5202 [hep-ph]:
Neutrino Mass Matrix with No Adjustable Parameters
Yoshio Koide and Hiroyukai Nishiura
On the basis of the so-called ``yukawaon" model,
we found out a special form of the neutrino mass matrix $M_\nu$
which gives reasonable predictions.
The $M_\nu$ is given by a multiplication form made of
charged lepton mass matrix $M_e$ and up-quark mass
matrix $M_u$. This $M_\nu$ has no adjustable parameters
except for those in $M_e$ and $M_u$.
Here, $M_e$ and $M_u$ are described by one parameter
$a_e$ (real) and two parameters $a_u$ (complex),
respectively, and those parameters are constrained
by their observed mass ratios. With this form of $M_\nu$,
in spite of having only three parameters,
the $M_\nu$ can give reasonable predictions
$\sin^2 2\theta_{atm} \simeq 0.99$, $\sin^2 2\theta_{13} \simeq 0.015$,
$\Delta m^2_{21}/\Delta m^2_{32} \simeq 0.030$,
$\langle m_{ee}\rangle \simeq 0.0039$ eV, and so on,
by using observed values of $m_e/m_\mu$, $m_\mu/m_\tau$, $m_c/m_t$,
and $\sin^2 \theta_{solar}$ as input values.
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