19 research outputs found
Large Gauge Hierarchy in Gauge-Higgs Unification
We study a five dimensional SU(3) nonsupersymmetric gauge theory compactified
on and discuss the gauge hierarchy in the scenario of the
gauge-Higgs unification. Making use of calculability of the Higgs potential and
a curious feature that coefficients in the potential are given by discrete
values, we find two models, in which the large gauge hierarchy is realized,
that is, the weak scale is naturally obtained from an unique large scale such
as a grand unified theory scale or the Planck scale. The size of the Higgs mass
is also discussed in each model. One of the models we find realizes both large
gauge hierarchy and consistent Higgs mass, and shows that the Higgs mass
becomes heavier as the compactified scale becomes smaller.Comment: 21 pages, no figures, version to appear in PR
Effect of Bare Mass on the Hosotani Mechanism
It is pointed out that the existence of bare mass terms for matter fields
changes gauge symmetry patterns through the Hosotani mechanism. As a
demonstration, we study an SU(2) gauge model with massive adjoint fermions
defined on . It turns out that the vacuum structure changes at
certain critical values of , where stands for the bare mass (the
circumference of ). The gauge symmetry breaking patterns are different
from models with massless adjoint fermions. We also consider a supersymmmetric
SU(2) gauge model with adjoint hypermultiplets, in which the supersymmetry is
broken by bare mass terms for the gaugino and squark fields instead of the
Scherk-Schwarz mechanism.Comment: 10 pages, version to appear in Phys. Lett.
On Gauge Symmetry Breaking via Euclidean Time Component of Gauge Fields
We study gauge theories with/without an extra dimension at finite
temperature, in which there are two kinds of order parameters of gauge symmetry
breaking. The one is the zero mode of the gauge field for the Euclidean time
direction and the other is that for the direction of the extra dimension. We
evaluate the effective potential for the zero modes in one-loop approximation
and investigate the vacuum configuration in detail. Our analyses show that
gauge symmetry can be broken only through the zero mode for the direction of
the extra dimension and no nontrivial vacuum configuration of the zero mode for
the Euclidean time direction is found.Comment: 22 pages, 6 figures, references and typos corrected, version to
appear in PR
Spontaneous Supersymmetry Breaking from Extra Dimensions
We propose a new spontaneous supersymmetry breaking mechanism, in which extra
compact dimensions play an important role. To illustrate our mechanism, we
study a simple model consisting of two chiral superfields, where one spatial
dimension is compactified on a circle . It is shown that supersymmetry is
spontaneously broken irrespective of the radius of the circle, and also that
the translational invariance for the -direction and a global symmetry are
spontaneously broken when the radius becomes larger than a critical radius.
These results are expected to be general features of our mechanism. We further
discuss that our mechanism may be observed as the O'Raifeartaigh type of
supersymmetry breaking at low energies.Comment: 10 pages, No figur
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.Comment: 17 pages, 1 figur
Dynamical Gauge-Higgs Unification in the Electroweak Theory
doublet Higgs fields are unified with gauge fields in the model of Antoniadis, Benakli and Quir\'{o}s' on the orbifold
. The effective potential for the Higgs fields (the
Wilson line phases) is evaluated. The electroweak symmetry is dynamically
broken to by the Hosotani mechanism. There appear light Higgs
particles. There is a phase transition as the moduli parameter of the complex
structure of is varied.Comment: 14 pages, 3 figures, v.
Multi-Higgs Mass Spectrum in Gauge-Higgs Unification
We study an SU(2) supersymmetric gauge model in a framework of gauge-Higgs
unification. Multi-Higgs spectrum appears in the model at low energy. We
develop a useful perturbative approximation scheme for evaluating effective
potential to study the multi-Higgs mass spectrum. We find that both
tree-massless and massive Higgs scalars obtain mass corrections of similar size
from finite parts of the loop effects. The corrections modify multi-Higgs mass
spectrum, and hence, the loop effects are significant in view of future
verifications of the gauge-Higgs unification scenario in high-energy
experiments.Comment: 32 pages; typos corrected and a few comments added, published versio
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.Comment: 14 pages, no figures, (v2)typos and errors corrected, (v3)the final
version to appear in PL
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.Comment: 18 pages, 7 figures, references corrected, minor correctio