Searcharxiv⌕ Search

arXiv subjects

Nobuhito Maru

Publications and source records attributed to Nobuhito Maru.

At least 91 records · Page 5Linked to original sources
arXiv2008

Finite Gluon Fusion Amplitude in the Gauge-Higgs Unification

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.

hep-ph↗
arXiv2008

Towards A Realistic Grand Gauge-Higgs Unification Scenario

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.

hep-ph↗
arXiv2008

Gauge-Higgs Unification at LHC

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.

hep-ph↗
arXiv2007

A Simple Model of Direct Gauge Mediation of Metastable Supersymmetry Breaking

We construct a model of direct gauge mediation of metastable SUSY breaking by simply deforming the Intriligator, Seiberg and Shih model in terms of a dual meson superpotential mass term. No extra matter field is introduced. The deformation explicitly breaks a U(1)_R symmetry and a pseudo moduli have a nonzero VEV at one-loop. Our metastable SUSY breaking vacuum turns out to be sufficiently long-lived. By gauging a subgroup of flavor symmetry, our model can directly couple to the standard model, which leads to nonvanishing gaugino mass generation. It is also shown that our model can evade the Landau pole problem. We show the parameters in the SUSY breaking sector are phenomenologically constrained.

hep-ph↗
arXiv2007

Supersymmetry Breaking and Radius Stabilization by Constant Boundary Superpotentials in Warped Space

Supersymmetry breaking and radius stabilization by constant superpotentials localized at boundaries is studied in a supersymmetric warped space model where a hypermultiplet, a compensator and a radion multiplet are taken into account. Soft mass induced by the anomaly mediation can be of the order of 100GeV and can be dominant compared to that mediated by bulk fields. A lighter physical mode composed of the radion and the moduli can have mass of the order of a TeV and the gravitino mass can be of the order of 10^7 GeV. The radius is stabilized by the presence of the constant boundary superpotentials. We also find that the mass splitting has an interesting dependence on the bulk mass parameter c.

hep-th↗
arXiv2007

Towards A Realistic 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. 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.

hep-ph↗
arXiv2007

Radius stabilization by constant boundary superpotentials in warped space

A warped space model with a constant boundary superpotential has been an efficient model both to break supersymmetry and to stabilize the radius, when hypermultiplet, compensator and radion multiplet are taken into account. In such a model of the radius stabilization, the radion and moduli masses, the gravitino mass and the induced soft masses are studied. We find that a lighter physical mode composed of the radion and the moduli can have mass of the order of a TeV and that the gravitino mass can be of the order of 10$^7$ GeV. It is also shown that soft mass induced by the anomaly mediation can be of the order of 100GeV and can be dominant compared to that mediated by bulk fields. Localized F terms and D terms are discussed as candidates of cancelling the cosmological constant. We find that there is no flavor changing neutral current problem in a wide range of parameters.

hep-th↗
arXiv2007

Calculable One-Loop Contributions to S and T Parameters in the Gauge-Higgs Unification

We investigate the one-loop contributions to S and T oblique parameteres in gauge-Higgs unification. We show that these parameters are finite in five dimensional space-time, but are divergent in more than five dimensions. Remarkably, however, we find that a particular linear combination of S and T parameters, S - 4 \cos θ_{W} T, becomes finite for six dimensional space-time, though each of these parameters is divergent. This is because, in the Gauge-Higgs unification scenario, the operators relevant for S and T parameters are not independent, but are included in a unique higher dimensional gauge invariant operator. Thus the predictable linear combination is model independent, irrespectibly of the detail of the matter content.

hep-ph↗
arXiv2007

Structure of S and T Parameters in Gauge-Higgs Unification

We investigate the divergence structure of one-loop corrections to S and T parameteres in gauge-Higgs unification. We show that these parameters are finite in five dimensions, but divergent in more than five dimensions. Remarkably, a particular linear combination of S and T parameters becomes finite in six dimension case, which is indicated from the operator analysis in a model independent way.

hep-ph↗
arXiv2006

Two-loop Calculation of Higgs Mass in Gauge-Higgs Unification: 5D Massless QED Compactified on S^1

We calculate the quantum corrections to the mass of the zero mode of the fifth component of the gauge field at two-loop level in a five dimensional massless QED compactified on S^1. We discuss in detail how the divergences are exactly canceled and the mass becomes finite. The key ingredients to obtain the result are the five dimensional gauge invariance and the Ward-Takahashi identity. We also evaluate the finite part of corrections.

hep-ph↗
arXiv2006

Supersymmetry Breaking by Constant Boundary Superpotentials in Warped Space

Supersymmetry breaking by constant (field independent) superpotentials localized at boundaries is studied in a supersymmetric warped space model. We calculate the Kaluza-Klein mass spectrum of the hypermultiplet. We take into account of the radion and the compensator supermultiplets, as well as the bulk mass $c$ for the hypermultiplet. The mass splitting is similar to that of the Scherk-Schwarz supersymmetry breaking (in flat space) for large $|c|$, and has an interesting dependence on the bulk mass parameter $c$. We show that the radius is stabilized by the presence of the constant boundary superpotentials.

hep-th↗
arXiv2006

Bulk Mass Effects in Gauge-Higgs Unification at Finite Temperature

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.

hep-ph↗
arXiv2006

Six Dimensional Gauge-Higgs Unification with an Extra Space S^2 and the Hierarchy Problem

We calculate one-loop radiative correction to the mass of Higgs identified with the extra space components of the gauge field in a six dimensional massive scalar QED compactified on a two-sphere. The radiatively induced Higgs mass is explicitly shown to be finite for arbitrary bulk scalar mass M. Furthermore, the remaining finite part also turns out to vanish, at least for the case of small M, thus suggesting that the radiatively induced Higgs mass exactly vanishes, in general. The non-zero "Kaluza-Klein" modes in the gauge sector are argued to have a Higgs-like mechanism and quantum mechanical N=2 supersymmetry, while the Higgs zero modes, as supersymmetric states, have a close relation with monopole configuration.

hep-th↗
arXiv2006

Effects of Bulk Mass in Gauge-Higgs Unification

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.

hep-ph↗
arXiv2005

Holographic Model for Hadrons in Deformed AdS5 Background

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.

hep-ph↗
arXiv2005

Gravitational Radius Stabilization in Supersymmetric Warped Compactification

We examine the possibility of the extra dimensional radius stabilization with only the gravity multiplet in the bulk and some couplings at orbifold fixed points in a supersymmetric Randall-Sundrum model. Unfortunately, we find that the radius cannot be stabilized in all the cases we consider. Depending on parameters in the model, the fifth dimension collapses or its radius goes to infinity. While the former case is theoretically disastrous, the latter implies that the so-called ``RS II'' model is automatically realized in our setup. Although the radius is not stabilized, there is nothing wrong with the resultant RS II model, because it is not only phenomenologically viable but also free from the gauge hierarchy problem thanks to its supersymmetric extension.

hep-th↗
arXiv2005

Aspects of Phase Transition in Gauge-Higgs Unification at Finite Temperature

We study the phase transition in gauge-Higgs unification at finite temperature. In particular, we obtain the strong first order electroweak phase transition for a simple matter content yielding the correct order of Higgs mass at zero temperature. Two stage phase transition is found for a particular matter content, which is the strong first order at each stage. We further study supersymmetric gauge models with the Scherk-Schwarz supersymmetry breaking. We again observe the first order electroweak phase transition and multi stage phase transition.

hep-th↗