arXiv subjects

Nobuhito Maru

Publications and source records attributed to Nobuhito Maru.

At least 19 recordsLinked to original sources

arXiv2026

Two Higgs Doublet Model from Six Dimensional Gauge Theory

We improve our previously proposed two Higgs doublet model of six-dimensional $SU(4)$ gauge theory compactified on an orbifold $T^2/Z_2$ by introducing the brane localized gauge kinetic terms. Since two Higgs doublets are identified with massless zero modes in extra spatial components of the six-dimensional gauge field, the Higgs sector in our model is constrained by the six-dimensional gauge symmetry. As a result, our Higgs potential at tree-level is automatically CP conserving and $Z_2$ symmetric, which are assumed by hand in the ordinary two Higgs doublet models. The scalar masses breaking the $Z_2$ symmetry softly are generated at one-loop. We show that the Standard Model Higgs mass can be obtained by tuning the size of the brane localized gauge kinetic terms as well as the electroweak symmetry breaking is realized. Other physical Higgs masses are predicted.

hep-ph↗

arXiv2025

Pseudo-Nambu-Goldstone Dark Matter in Flux Compactification

We study a six-dimensional U(1)$_χ$ gauge theory compactified on a magnetized torus, where the zero mode of the extra-dimensional gauge field (a Wilson-line (WL) scalar field) plays the role of a pseudo-Nambu-Goldstone (pNG) dark matter (DM) candidate. The pNG DM is naturally included by construction without introducing an additional scalar field. We show that the leading spin-independent DM-nucleus amplitude is suppressed by momentum transfer in our model as expected from the pNG DM model. This suppression allows the model to evade the current severe direct-detection bounds while achieving the observed thermal relic abundance in well-defined regions of parameter space.

hep-ph↗

arXiv2025

Dyons in higher-dimensional gauge theories

We discuss the 't Hooft-Polyakov (TP) monopole and then dyon in the framework of higher dimensional gauge theories, such as gauge-Higgs unification models. First, we point out that the Bogomol'nyi-Prasad-Sommerfield (BPS) monopole is nothing but a self-dual gauge field in the 4-dimensional (4D) space including the extra dimension, which is argued to lead to a consequence that the mass of the BPS monopole $M_{\rm TPM}$ and therefore the vacuum expectation value (VEV) of the Higgs field are topologically quantized. In literatures, there exist related arguments on the calorons, which may be understood to be a composition of a pair of constituent monopole and anti-monopole, with each constituent carrying fractional topological charge, while the net topological charge carried by the caloron is unity. From the viewpoint of the caloron, our conclusion of the quantized monopole mass corresponds to the special case, where only a single monopole exists that carries the net topological charge. Next, the argument is generalized to the case of dyon. The mass of the BPS dyon, $M_{\rm BPS}$, is still proportional to the quantized Higgs VEV, though it also depends on a parameter $μ$, denoting the ratio of the electric and magnetic charges of the dyon. In the 5D gauge theories the Chern-Simons term is induced at the quantum level, which, after the extra space component of the gauge field is replaced by its VEV, produces the $θ$ term. Then, through the Witten effect we reach to an interesting conclusion that the parameter $μ$ and therefore $M_{\rm BPS}$ are discretized. In addition, we propose a numerical method to obtain the field configurations and the mass of the non-BPS dyons by use of ``modified" gradient flow equations.

hep-th↗

arXiv2025

Family Unification in a Six Dimensional Theory with an Orthogonal Gauge Group

We propose a simple model of family unification, which is a six dimensional $SO(20)$ gauge theory with a single fermion in the spinorial representation. After compactification to five dimensions, our model gives a five dimensional model where the Standard Model Higgs field is unified into the fifth component of the five dimensional gauge field as well as three generations of quarks and leptons are unified into a single spinor field.

hep-ph↗

arXiv2025

Electroweak Symmetry Breaking in Sp(6) Gauge-Higgs Unification Model

We study the electroweak symmetry breaking in a five dimensional $Sp(6)$ gauge-Higgs unification model where the weak mixing angle is predicted to be $\sin^2 θ_W=1/4$ at the compactification scale. We find that the correct pattern of electroweak symmetry breaking and a viable Higgs mass are realized by introducing a 4-rank totally symmetric representation and several adjoint fermions additionally.

hep-ph↗

arXiv2025

SU(7) Grand Gauge-Higgs Unification

We propose a model of six dimensional $SU(7)$ grand gauge-Higgs unification compactified on $S^1/Z_2 /times S^1/Z_2$, which is a six dimensional extension of five dimensional $SU(4)$ gauge-Higgs unification predicting the weak mixing angle $/sin^2 /theta_W=1/4$ at the compactification scale. We investigate whether the correct pattern of electroweak symmetry breaking is realized in our model. We find some solutions providing the electroweak symmetry breaking and a realistic Higgs mass. Corresponding to each solution, the compactification scale of the fifth dimension is predicted. Furthermore, we evaluate the weak mixing angle at the weak scale by using one-loop renormalization group equation and find it to be in good agreement with the experimental data.

hep-ph↗

arXiv2024

Attempt at Constructing a Model of Grand Gauge-Higgs Unification with Family Unification

We discuss a possibility whether a model of grand gauge-Higgs unification incorporating family unification in higher dimensions can be constructed. We first extend a five dimensional $SU(6)$ grand gauge-Higgs unification model to a five dimensional $SU(7)$ grand gauge-Higgs unification model compactified on an orbifold $S^1/Z_2$ to obtain three generations of quarks and leptons after symmetrybreaking of the larger family unified gauge group. A prescription of constructing a six dimensional $SU(N)$ grand gauge-Higgs unification model including a five dimensional $SU(7)$ grand gauge-Higgs unification after compactifying the sixth dimension on an orbifold $S^1/Z_2$ is given. We find a six dimensional $SU(14)$ grand gauge-Higgs unification model with a set of representations containing three generations of quarks and leptons.

hep-ph↗

arXiv2024

New Models of $SU(6)$ Grand Gauge-Higgs Unification

A five dimensional $SU(6)$ grand gauge-Higgs unification compactified on $S^1/Z_2$ is discussed. We propose new sets of the $SU(6)$ representations where the quarks and leptons in one generation are embedded and there is no extra massless exotic fermions absent in the Standard Model. The correct electroweak symmetry breaking pattern can be realized by introducing some adjoint fermions. We also analyze whether a viable Higgs mass can be obtained.

hep-ph↗

arXiv2024

Toward Realistic Models in $T^2/\mathbb{Z}_2$ Flux Compactification

We consider a six dimensional gauge theory compactified on $T^2/\mathbb{Z}_2$ with magnetic flux. The configurations of models are classified by winding numbers at the fixed points. Requiring the existence of generation numbers and Yukawa coupling, we see that allowed and forbidden configurations are described by geometry of winding numbers.

hep-ph↗

arXiv2023

Electroweak Symmetry Breaking in Two Higgs Doublet Model from 6D Gauge-Higgs Unification on $T^2/Z_2$

Electroweak symmetry breaking is explored in a two Higgs doublet model based on a six dimensional $SU(4)$ gauge-Higgs unification compactified on an orbifold $T^2/Z_2$. The remarkable property of this model is a prediction of realistic weak mixing angle $\sin^2 θ_W = 1/4$ at the compactification scale. We calculate one-loop effective potential of the Standard Model Higgs boson from the contributions of the gauge boson and the fermion in a four-rank totally symmetric tensor where top quark is included. We find that the electroweak symmetry breaking certainly takes place.

hep-ph↗

arXiv2023

Wilson-line Scalar Mass in Flux Compactification on an Orbifold $T^2/Z_2$

In a torus compactification with magnetic flux, the scalar field generated from the higher dimensional gauge field becomes the Nambu-Goldstone boson of the translational symmetry in extra spaces and the mass of the scalar field is not allowed. In this paper, we explicitly show that the one-loop quantum correction to the mass of the scalar field is generated at fixed points in a case of an orbifold compactification $T^2/Z_2$ with magnetic flux. This is because the scalar field is a pseudo Nambu-Goldstone boson as a result of explicit breaking of the translational symmetry by the fixed points. This result might be possible to shed a new light on the solution of the hierarchy problem.

hep-th↗

arXiv2023

Fermion Mass Hierarchy and Mixing in simplified Grand Gauge-Higgs Unification

Grand gauge-Higgs unification of five dimensional SU(6) gauge theory on an orbifold $S^1 / Z_2$ with localized gauge kinetic terms is discussed. The Standard model (SM) fermions on the boundaries and some massive bulk fermions coupling to the SM fermions are introduced. The number of the bulk fermions is reduced compared to the previous model, which reproduces the generation mixing of the SM fermions in addition to the SM fermion mass hierarchy by mild tuning the bulk masses and parameters of the localized gauge kinetic terms.

hep-ph↗

arXiv2023

Analytic construction of sphaleron-like solution invoking higher dimensional gauge theory

We perform analytic construction of a sphaleron-like solution in the 4-dimensional (4D) space-time invoking the framework of 5D SU(2) gauge theory. By the sphaleron-like solution we mean a static finite energy solution to the equation of motion, which carries the Chern-Simons number $N_\text{CS}=\frac{1}{2}$. Since we are interested in the static solution in the low-energy effective theory, we focus on the part of the action which contains only the gauge fields in the 4D space (not space-time), $(A_{i}, A_{y}) (i = 1,2,3)$ and keep only the Kaluza-Klein zero modes of these fields. Interestingly, the self-duality condition in this 4D space is known to be nothing but the BPS condition for the 't Hooft-Polyakov monopole, once the extra-space component $A_y$ is identified with the adjoint scalar, needed for the monopole solution. Thus, the sphaleron-like solution is based on the BPS monopole embedded in the higher dimensional space-time, which may be interpreted as a self-dual gauge field. By use of the lesson we learn in the case of the instanton in ordinary 4D space-time, we achieve the sphaleron-like configuration of $A_{i}$, which carries $N_\text{CS} = \frac{1}{2}$. As a characteristic feature of this construction invoking higher dimensional gauge theory, in clear contrast to the case of the ordinary BPS monopole, the VEV of the adjoint scalar is topologically fixed, and therefore the mass of the sphaleron-like solution is determined to be $M_\text{sp} = \frac{4π}{g_{4}^{2}}\frac{1}{R}$ ($g_{4}$: 4D gauge coupling constant, $R$: the radius of the circle as the extra space). We also argue that the sphaleron-like solution may be regarded as a saddle point of the energy in the space of static field configurations.

hep-th↗

arXiv2022

Cosmological Collider Signals of Non-Gaussianity from Higgs boson in GUT

Cosmological Collider Physics gives us the opportunity to probe high-energy physics from observing the spacetime fluctuations generated during inflation imprinted on the cosmic microwave background. In other words, it is a method to investigate physics on energy scales that cannot be reached by terrestrial accelerators by means of precise observations of the universe. In this paper, we focus on the case where the GUT scale is close to the energy scale of inflation, and calculate three point function of inflaton by exchanging the Higgs boson in GUT at tree level. The results are found to be consistent with the current observed restrictions on non-Gaussianity without a drastic fine tuning of parameters, and it might be possible to detect the signature of the Higgs boson in GUT by 21cm spectrum, future LSS and future CMB depending on our model parameters.

hep-ph↗

arXiv2022

Gauge Symmetry Breaking in Flux Compactification with Wilson-line Scalar Condensate

We discuss the gauge symmetry breaking of six dimensional theories in flux compactification with a magnetic flux background and a constant vacuum expectation value (VEV) for the scalar fields, which are zero modes of extra spatial components of the gauge field. Although the effective potential for the scalar fields are known not to be generated classically and radiatively in a magnetic flux background only, the one-loop effective potential is shown to be generated by the effects of the non-zero constant VEV. As illustrations, we calculate the one-loop effective potential in SU(2) and SU(3) Yang-Mills theories. In both cases, we find that the potential minimum is located at non-zero VEV and the gauge symmetry breaking takes place.

hep-th↗

arXiv2022

On the vacuum structure of gauge-Higgs unification models

In this paper, we discuss the vacuum structure of the gauge-Higgs unification theory, which is one of the attractive candidates of physics beyond the standard model. This scenario has a remarkable feature, namely it has infinitely degenerate vacua due to the characteristic periodic potential of the Higgs filed, to be identified with the extra space component of the higher dimensional gauge field. We address a question, whether to form the superposition of such degenerate vacua, like the $θ$-vacuum in QCD, is necessary or not, in order to realize the true vacuum state of the theory. We derive gauge field configuration which describes the transition between neighboring vacua, like the instanton (or anti-instanton) solution in QCD, and the corresponding Euclidean action in two models. In a simplified 2-dimensional U(1) model, the derived configuration to describe the transition is shown to have finite Euclidean action, and accordingly the "$θ$-vacuum" and the resultant "$θ$-term" are formulated. In a realistic 5D U(1) model, however, the gauge field configuration to describe the transition is shown to have infinite Euclidean action and therefore the tunneling probability between the degenerate vacua vanishes. Thus the superposition of the degenerate vacua is not necessary.

hep-th↗

arXiv2022

Gauge Coupling Unification in simplified Grand Gauge-Higgs Unification

Grand gauge-Higgs unification of five dimensional SU(6) gauge theory on an orbifold $S^1/Z_2$ with localized gauge kinetic terms is discussed. The Standard model (SM) fermions on the boundaries and some massive bulk fermions coupling to the SM fermions on the boundary are introduced. Taking the power-law running contributions from the bulk fields into account, perturbative gauge coupling unification is shown to be realized at around $10^{14}$ GeV, which is a few order smaller than the unification scale of four dimensional grand unified theories.

hep-ph↗

arXiv2021

Nonvanishing Finite Scalar Mass in Flux Compactification

We study possibilities to realize a nonvanishing finite Wilson line (WL) scalar mass in flux compactification. Generalizing loop integrals in the quantum correction to WL mass at one-loop, we derive the conditions for the loop integrals and mode sums in one-loop corrections to WL scalar mass to be finite. We further guess and classify the four-point and three-point interaction terms satisfying these conditions. As an illustration, the nonvanishing finite WL scalar mass is explicitly shown in a six dimensional scalar QED by diagrammatic computation and effective potential analysis. This is the first example of finite WL scalar mass in flux compactification.

hep-th↗