掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/JHEP08(2019)054

掲載種別：研究論文（学術雑誌）  

DOI： 10.1093/ptep/ptz083

掲載種別：研究論文（学術雑誌）  

A new vector dark matter (DM) scenario in the context of the gauge-Higgs
unification (GHU) is proposed. The DM particle is identified with an
electric-charge neutral component in an $SU(2)_L$ doublet vector field with the
same quantum number as the Standard Model Higgs doublet. Since such an
$SU(2)_L$ doublet vector field is incorporated in any models of the GHU
scenario, it is always a primary and model-independent candidate for the DM in
the scenario. The observed relic density is reproduced through a DM pair
annihilations into the weak gauge bosons with a TeV-scale DM mass, which is
nothing but the compactification scale of extra-dimensions. Due to the
higher-dimensional gauge structure of the GHU scenario, a pair of the DM
particles has no direct coupling with a single $Z$-boson/Higgs boson, so that
the DM particle evades the severe constraint from the current direct DM search
experiments.

DOI： 10.1103/PhysRevD.98.075021

掲載種別：研究論文（学術雑誌）  

DOI： 10.11316/jpsgaiyo.73.2.0_18

CiNii Article

掲載種別：研究論文（学術雑誌）   共著区分：単著  

DOI： 10.1142/S0217751X17470200

掲載種別：研究論文（学術雑誌）  

We propose a Minimal Dark Matter (MDM) scenario in the context of a simple
gauge-Higgs Unification (GHU) model based on the gauge group SU(3) x U(1)' in
5-dimensional Minkowski space with a compactification of the 5th dimension on
S^1/Z_2 orbifold. A pair of vector-like SU(3) multiplet fermions in a
higher-dimensional representation is introduced in the bulk, and the DM
particle is identified with the lightest mass eigenstate among the components
in the multiplets. In the original model description, the DM particle
communicates with the Standard Model (SM) particles only through the bulk gauge
interaction, and hence our model is the GHU version of the MDM scenario. There
are two typical realizations of the DM particle in 4-dimensional effective
theory: (i) the DM particle is mostly composed of the SM SU(2)_L multiplets, or
(ii) the DM is mostly composed of the SM SU(2)_L singlets. Since the case (i)
is very similar to the original MDM scenario, we focus on the case (ii), which
is a realization of the Higgs-portal DM scenario in the context of the GHU
model. We identify an allowed parameter region to be consistent with the
current experimental constraints, which will be fully covered by the direct
dark matter detection experiments in the near future. In the presence of the
bulk multiplet fermions in higher-dimensional $SU(3)$ representations, we
reproduce the 125 GeV Higgs boson mass through the renormalization group
evolution of Higgs quartic coupling with the compactification scale of 10-100
TeV.

DOI： 10.1103/PhysRevD.96.115023

掲載種別：研究論文（学術雑誌）  

We propose a Majorana fermion dark matter in the context of a simple
gauge-Higgs Unification (GHU) scenario based on the gauge group $SU(3)$ x
$U(1)'$ in 5-dimensional Minkowski space with a compactification of the 5th
dimension on $S^1/Z_2$ orbifold. The dark matter particle is identified with
the lightest mode in $SU(3)$ triplet fermions additionally introduced in the
5-dimensional bulk. We find an allowed parameter region for the dark matter
mass around a half of the Standard Model Higgs boson mass, which is consistent
with the observed dark matter density and the constraint from the LUX 2016
result for the direct dark matter search. The entire allowed region will be
covered by, for example, the LUX-ZEPLIN dark matter experiment in the near
future. We also show that in the presence of the bulk $SU(3)$ triplet fermions
the 125 GeV Higgs boson mass is reproduced through the renormalization group
evolution of Higgs quartic coupling with the compactification scale of around
$10^8$ GeV.

DOI： 10.1007/JHEP07(2017)048

掲載種別：研究論文（学術雑誌）  

DOI： 10.11316/jpsgaiyo.72.2.0_24

CiNii Article

掲載種別：研究論文（学術雑誌）  

We examine trilinear gauge boson couplings (TGCs) in the context of the
$SU(3)_W\otimes U(1)'$ gauge-Higgs unification scenario. The TGCs play
important roles in the probes of the physics beyond the standard model, since
they are highly restricted by the experiments. We discuss mass spectrum of the
neutral gauge boson with brane-localized mass terms carefully and find that the
TGCs and $\rho$ parameter may deviate from standard model predictions. Finally
we put a constraint from these observables and discuss the possible parameter
space.

DOI： 10.1093/ptep/ptw088

掲載種別：研究論文（学術雑誌）   共著区分：単著  

A recently proposed new mechanism of D-term triggered dynamical supersymmetry
breaking is reviewed. Supersymmetry is dynamically broken by nonvanishing
D-term vacuum expectation value, which is realized as a nontrivial solution of
the gap equation in the self-consistent approximation as in the case of
Nambu-Jona-Lasinio model and BCS superconductivity.

DOI： 10.1093/ptep/ptw018

掲載種別：研究論文（学術雑誌）  

DOI： 10.1140/epjp/i2015-15168-3

掲載種別：研究論文（学術雑誌）  

We address a question whether the recently observed Higgs mass $M_{H} = 126$
GeV, of the order of the weak scale $M_{W}$, is calculable as a finite value in
the scnenario of gauge-Higgs unification. In the scenario formulated on a flat
5-dimensional space-time, the Higgs mass is calculable, being protected under
the quantum correction by gauge invariance, though the predicted Higgs mass is
generally too small compared with $M_{W}$. In the 6-dimensional SU(3) model,
however, a suitable orbifolding is known to lead to a mass of the order of
$M_{W}$: $M_{H} = 2M_{W}$ at the tree level, which has some similarity to the
corresponding prediction by the MSSM, $M_{H}$ leq (cos beta) $M_{Z}$. We
demonstrate first by a general argument and secondly by explicit calculations
that, even though the quantum correction to the quartic self-coupling of the
Higgs field is UV-divergent, its deviation from that of $g^{2}$ is calculable,
and therefore two observables, $M_{H}^{2}$ and Delta equiv
$(M_{H}/2M_{W})^{2}-1$, are both calculable in the gauge-Higgs unification
scenario. The implication of the precise value 126 GeV to the compactification
scale and the bulk mass of the matter field in our model is also discussed.

DOI： 10.1093/ptep/ptv030

掲載種別：研究論文（学術雑誌）  

DOI： 10.3390/sym7010193

掲載種別：研究論文（学術雑誌）  

In our previous paper, we have investigated effects of a simple gauge-Higgs
unification model on the diphoton signal events from the Higgs boson production
at the Large Hadron Collider. We have found that in this model the effective
Higgs-to-diphoton coupling can be enhanced by 1-loop corrections with
Kaluza-Klein (KK) modes of bulk fields. This result can be an explanation for
the observed excess of the signal strength in the Higgs to diphoton decay
channel. In this paper, we investigate KK-mode effects on another Higgs boson
decay mode, H to Z gamma. One naturally expects that the KK modes also
contribute to the effective H-Z-gamma coupling and can cause some deviation for
the H to Z gamma decay mode from the Standard Model prediction. Revealing a
correlation between the KK-mode effects on the Higgs-to-diphoton and H-Z-gamma
couplings is an interesting topic in terms of a possibility to discriminate a
variety of models for physics beyond the Standard Model. We show a very
striking result for the gauge-Higgs unification model, namely, the absence of
KK-mode contributions to the H-Z-gamma coupling at the 1-loop level. This is a
very specific and general prediction of the gauge-Higgs unification scenario.

DOI： 10.1103/PhysRevD.88.037701

掲載種別：研究論文（学術雑誌）  

We present the mechanism of the dynamical supersymmetry breaking at the
metastable vacuum recently uncovered in the N=1 U(N) supersymmetric gauge
theory that contains adjoint superfields and that is specified by Kahler and
non-canonical gauge kinetic functions and a superpotential whose tree vacua
preserve N=1 supersymmetry. The overall U(1) serves as the hidden sector and no
messenger superfield is required. The dynamical supersymmetry breaking is
triggered by the non-vanishing D term coupled to the observable sector, and is
realized by the self-consistent Hartree-Fock approximation of the NJL type
while it eventually brings us the non-vanishing F term as well. It is shown
that theoretical analysis is resolved as a variational problem of the effective
potential for three kinds of background fields, namely, the complex scalar, and
the two order parameters D and F of supersymmetry, the last one being treated
perturbatively. We determine the stationary point and numerically check the
consistency of such treatment as well as the local stability of the scalar
potential. The coupling to the N = 1 supergravity is given and the gravitino
mass formula is derived.

DOI： 10.1103/PhysRevD.88.025012

掲載種別：研究論文（学術雑誌）  

We discuss flavor mixing and resultant flavor changing neutral current rocesses in the SU(3) circle times SU(3)(color) gauge-Higgs unification scenario. To achieve flavor violation is a challenging issue in the scenario, since the Yukawa couplings are originally higher dimensional gauge interactions. We argue that the presence of Z(2)-odd bulk masses of fermions plays a crucial role as the new source of flavor violation. Although introducing brane-localized mass terms in addition to the bulk masses is necessary to realize flavor mixing, if the bulk masses were universal among generations, the flavor mixing and flavor changing neutral current processes are known to disappear. We also discuss whether natural flavor conservation is realized in the scenario. It is shown that the new source of flavor violation leads to flavor changing neutral current processes at the tree level due to the exchange of non-zero Kaluza-Klein gauge bosons. As a typical example we calculate the rate of K-0 - (K) over bar (0) mixing due to the non-zero Kaluza-Klein gluon exchange at the tree level. The obtained result for the mass difference of neutral kaon is suppressed by the inverse powers of the compactification scale. By comparing our prediction with the data we obtain the lower bound of the compactification scale as a function of one unfixed parameter of the theory, which is of O(10) TeV, except for some extreme cases. We argue that the reason to get such rather mild lower bound is the presence of "GIM-like" mechanism, which is a genuine feature of GHU scenario.

DOI： 10.1007/JHEP11(2010)150

掲載種別：研究論文（学術雑誌）  

We address the challenging issue of how CP violation is realized in higher dimensional gauge theories without higher dimensional elementary scalar fields. In such theories interactions are basically governed by a gauge principle and therefore to get CP violating phases is a nontrivial task. It is demonstrated that CP violation is achieved as the result of compactification of extra dimensions, which is incompatible with the 4-dimensional CP transformation. As a simple example we adopt a 6-dimensional U(1) model compactified on a 2-dimensional orbifold T2/Z4. We argue that the 4-dimensional CP transformation is related to the complex structure of the extra space and show how the Z4 orbifolding leads to CP violation. We confirm by explicit calculation of the interaction vertices that CP violating phases remain even after the rephasing of relevant fields. For completeness, we derive a rephasing invariant CP violating quantity, following a similar argument in the Kobayashi-Maskawa model which led to the Jarlskog parameter. As an example of a CP violating observable we briefly comment on the electric dipole moment of the electron. © 2010 The American Physical Society.

DOI： 10.1103/PhysRevD.81.076006

掲載種別：研究論文（学術雑誌）  

We study the neutron electric dipole moment (EDM) in a five-dimensional SU(3) gauge-Higgs unification compactified on M4×S1/Z2 space-time including a massive fermion. We point out that to realize the CP violation is a nontrivial task in the gauge-Higgs unification scenario and argue how the CP symmetry is broken spontaneously by the vacuum expectation value of the Higgs, the extra space component of the gauge field. We emphasize the importance of the interplay between the vacuum expectation value of the Higgs and the Z2-odd bulk mass term to get physically the CP violation. We then calculate the one-loop contributions to the neutron EDM as the typical example of the CP violating observable and find that the EDM appears already at the one-loop level, without invoking the three-generation scheme. We then derive a lower bound for the compactification scale, which is around 2.6 TeV, by comparing the contribution due to the nonzero Kaluza-Klein modes with the experimental data. © 2009 The American Physical Society.

DOI： 10.1103/PhysRevD.80.055025

掲載種別：研究論文（学術雑誌）  

We discuss the anomalous magnetic moment of fermion in a realistic SU(3) model of gauge-Higgs unification compactified on an orbifold S1/Z2 including Z2-odd bulk mass for fermions. An operator analysis implies that the anomalous magnetic moment should be finite and predictable, even though higher dimensional gauge theories are nonrenormalizable. Our main purpose is to clarify the cancellation mechanism of the UV divergences appearing in various types of Feynman diagrams. The cancellation of divergence turns out to take place between the contributions of the partners in the Higgs-like mechanism present in the nonzero Kaluza-Klein modes to form massive gauge bosons. It is also argued that the cancellation may be attributed to the quantum mechanical supersymmetry hidden in the scenario of gauge-Higgs unification. © 2009 The American Physical Society.

DOI： 10.1103/PhysRevD.79.075018

掲載種別：記事・総説・解説・論説等（学術雑誌）  

In this manuscript, a unified approach to hadron physics from holographic
point of view is described. After introduction of a general setup for
meson-nucleon system based on the bottom-up approach of QCD (AdS/QCD), as an
illustration, we specifically examine meson-nucleon couplings. This is an
example of the notion we call "holographic unification" in hadron physics.

DOI： 10.1140/epjc/s10052-009-1096-x

掲載種別：記事・総説・解説・論説等（学術雑誌）  

We propose a new Universal Extra Dimensional model that is defined on a
six-dimensional spacetime which has a two-sphere orbifold $S^2/Z_2$ as an
extra-space. We specify our model by choosing the gauge symmetry as
SU(3)$\timesSU(2)\timesU(1)_Y \timesU(1)_X$, introducing field contents in
six-dimensions as their zero modes correspond to the Standard model particles,
and determining a boundary condition of these fields on orbifold $S^2/Z_2$. A
background gauge field that belongs to U(1)$_X$ is introduced there, which is
necessary to obtain massless chiral fermions in four-dimensional spacetime. We
then analyze Kaluza-Klein(KK) mode expansion of the fields in our model and
derive the mass spectrum of the KK particles. We find that the lightest KK
particles are the 1st KK particle of massless gauge bosons at tree level. We
also discuss the KK parity of the KK modes in our model and confirm the
stability of the lightest KK particle which is important for dark matter
physics.

DOI： 10.1016/j.nuclphysb.2009.11.023

掲載種別：記事・総説・解説・論説等（学術雑誌）   共著区分：単著  

We show that the gluon fusion amplitude in the gauge-Higgs unification
scenario is finite in any dimension regardless of its nonrenormalizability.
This result is supported by the fact that the local operator describing the
gluon fusion process is forbidden by the higher dimensional gauge invariance.
We explicitly calculate the gluon fusion amplitude in an arbitrary dimensional
gauge-Higgs unification model and indeed obtain the finite result.

DOI： 10.1142/S0217732308028247

掲載種別：記事・総説・解説・論説等（学術雑誌）   共著区分：単著  

In this talk, we discuss an attempt to construct a realistic model of the
grand gauge-Higgs unification. We investigate a 5D SU(6) grand gauge-Higgs
unification model compactified on an orbifold S^1/Z_2. Ordinary quarks and
leptons, together with right-handed neutrinos, are just accommodated into a
minimal set of representations of the gauge group, without introducing any
exotic states in the same representations. The proton decay turns out to be
forbidden at least at the tree level. We also find a correct electroweak
symmetry breaking SU(2)_L \times U(1)_Y \to U(1)_{em} is easily realized by
introducing suitable number of adjoint fermions.

DOI： 10.1063/1.2939048

掲載種別：記事・総説・解説・論説等（学術雑誌）  

The zero mode of an extra-dimensional component of gauge potentials serves as a 4D Higgs field in the gauge-Higgs unification. We examine QED on M 4 × S1 and determine the mass and potential of a 4D Higgs field (the A5, component) at the two loop level with gauge invariant regularization. It is seen that the mass is free from divergences and independent of the renormalization scheme.

DOI： 10.1143/PTP.118.1053

掲載種別：記事・総説・解説・論説等（学術雑誌）  

Higgs boson production by the gluon fusion and its decay into two photons at
the LHC are investigated in the context of the gauge-Higgs unification
scenario. The qualitative behaviors for these processes in the gauge-Higgs
unification are quite distinguishable from those of the Standard Model and the
universal extra dimension scenario because of the overall sign difference for
the effective couplings induced by one-loop corrections through Kaluza-Klein
(KK) modes. For the KK mode mass smaller than 1 TeV, the Higgs productions
cross section and its branching ratio into two photons are sizably deviated
from those in the Standard Model. Associated with the discovery of Higgs boson,
this deviation may be measured at the LHC.

DOI： 10.1103/PhysRevD.77.055010

掲載種別：記事・総説・解説・論説等（学術雑誌）  

We show that the anomalous magnetic moment of fermion in the gauge-Higgs
unification is finite in any spacetime dimensions, which is a new predictive
physical observable similar to the Higgs mass.

DOI： 10.1103/PhysRevD.76.075009

掲載種別：記事・総説・解説・論説等（学術雑誌）  

We investigate a 5D SU(6) grand gauge-Higgs unification model compactified on
an orbifold S^1/Z_2. Ordinary quarks and leptons, together with right-handed
neutrinos, are just accommodated into a minimal set of representations of the
gauge group, without introducing any exotic states. The proton decay turns out
to be forbidden at least at the tree level. We also find a correct electroweak
symmetry breaking SU(2)_L \times U(1)_Y \to U(1)_{em} is easily realized by
introducing suitable number of adjoint fermions.

DOI： 10.1016/j.physletb.2007.07.053

掲載種別：記事・総説・解説・論説等（学術雑誌）  

We study the bulk mass effects on the electroweak phase transition at finite
temperature in a five dimensional SU(3) gauge-Higgs unification model on an
orbifold. We investigate whether the Higgs mass satisfying the experimental
lower bound can be compatible with the strong first order phase transition
necessary for a successful electroweak baryogenesis. Our numerical results show
that the above statement can be realized by matter with bulk mass yielding a
viable Higgs mass. We also find an interesting case where the heavier Higgs
gives the stronger first order phase transition.

DOI： 10.1103/PhysRevD.74.015017

掲載種別：記事・総説・解説・論説等（学術雑誌）  

We study effects of bulk mass on electroweak symmetry breaking and Higgs mass
in the scenario of five dimensional SU(3) gauge-Higgs unification defined on
M^4\times S^1/Z_2. The asymptotic form of effective potential for the Higgs
field is obtained, from which a transparent and useful expression for the Higgs
mass is found. The small vacuum expectation values (VEV) for Higgs field can be
realized by choosing bulk mass parameters approriately for a fixed set of
matter content. The bulk mass for periodic fermion field, in general, has
effects to make the Higgs mass less heavy. On the other hand, the bulk mass for
antiperiodic field does not directly affect the Higgs mass, but it contributes
to increase or decrease the Higgs mass, depending on how small the VEV is
induced due to the antiperiodic field. We give numerical examples to confirm
these effects, in which the role of the bulk mass is also definitely clear.

DOI： 10.1016/j.physletb.2006.04.044

掲載種別：記事・総説・解説・論説等（学術雑誌）  

Several physical quantities of light hadrons are examined by a new
holographic model of QCD, which is the modified version of the one proposed by
Erlich et al. defined on AdS${}_5$. In our model, AdS${}_5$ is deformed by a
non-trivial bulk scalar, this is corresponding to adding the mass term of the
adjoint fermions to the 4d SYM theory dual to the gravity on AdS${}_5$. We find
that this deformation should be taken to be rather small, but its important
effects are also seen.

DOI： 10.1016/j.physletb.2005.12.004

掲載種別：記事・総説・解説・論説等（学術雑誌）  

The structure of Yukawa coupling matrices is investigated in type IIA T-6/(Z(2) x Z(2)) orientifold models with intersecting D-branes. Yukawa coupling matrices are difficult to be made realistic in conventional models in which the generation structure emerges by the multiple intersection of D-branes in the factorized T-6 = T-2 x T-2 x T-2. We study the new type of favor structure, where Yukawa couplings are dynamically generated, and show this type of models lead to non-trivial structures of Yukawa coupling matrices, which can be realistic.

DOI： 10.1140/epjc/s2005-02166-4

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