Yuki Adachi

Finite anomalous magnetic moment in the gauge-Higgs unification

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.

Neutron electric dipole moment in the gauge-Higgs unification

We study the neutron electric dipole moment (EDM) in a five-dimensional SU(3) gauge-Higgs unification compactified on M{sup 4}xS{sup 1}/Z{sub 2} 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 Z{sub 2}-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.

More on the finiteness of the anomalous magnetic moment in the gauge-Higgs unification

We discuss the anomalous magnetic moment of fermion in a realistic SU(3) model of gauge-Higgs unification compactified on an orbifold S{sup 1}/Z{sub 2} including Z{sub 2}-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.

Flavor Mixing in Gauge-Higgs Unification

We discuss flavor mixing and resultant flavor changing neutral current processes in the SU(3) ⊗ 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 Z2-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

D0 − {\overline {\text{D}}^0} mixing in gauge-Higgs unification

{K^0} - {\overline K^0}

B0−B¯0mixing in gauge-Higgs unification

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

Lower Bound for Compactification Scale from Muon g - 2 in the Gauge-Higgs Unification

\mathcal{O}\left( {10} \right)

Deviation of yukawa coupling and Higgs decay in gauge-Higgs Unification

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.

Revisiting electroweak symmetry breaking and the Higgs boson mass in gauge-Higgs unification

A bstractWe discuss flavor mixing and resulting Flavor Changing Neutral Current (FCNC) in the SU(3) ⊗ SU(3)color gauge-Higgs unification. As the FCNC process we calculate the rate of D0 −

μ term and supersymmetry breaking from 6D theory

{\overline {\text{D}}^0}