arXiv subjects

Yutaka Hosotani

Publications and source records attributed to Yutaka Hosotani.

At least 73 records · Page 4Linked to original sources

arXiv2006

Physics Consequences of Extra-Dimensional Gauge-Higgs Unification

In the dynamical gauge-Higgs unification of electroweak interactions, the 4D Higgs field is identified with the low energy mode of the extra-dimensional component of the gauge potentials. In the Randall-Sundrum warped spacetime, in particular, the Higgs boson mass is predicted in the range 120 GeV - 290 GeV. The universality of weak interactions is slightly broken by magnitudes of 10^{-8}, 10^{-6} and 10^{-2} for μ-e, τ-e and t-e, respectively.

hep-ph↗

arXiv2005

Unified Theory of Elementary Particles -- in Search of Extra Dimensions -----

Even though the unified theory of electroweak interactions is very successful at low energies, there remains one part to be confirmed. It is the sector involving Higgs particles. Those Higgs particles are expected to be discovered. It has been shown recently that Higgs particles can be viewed as gauge fields in higher dimensional gauge theory. The mass of a Higgs particle and its coupling to other particles are constrained by the gauge principle. In this scenario the mass of a Higgs particle is predicted to be in the range of 120 GeV - 290 GeV, exactly in the range explored at LHC, provided that the extra dimension is curved and warped. Thus physics of extra dimensions can manifest itself in collider experiments at the LHC energies.

hep-ph↗

arXiv2005

Dynamical Gauge Symmetry Breaking by Wilson Lines in the Electroweak Theory

In higher dimensional gauge theory, dynamics of non-Abelian Aharonov-Bohm phases induces gauge symmetry breaking through the Hosotani mechanism. Higgs fields in the four-dimensional spacetime are identified with the extra-dimensional components of the gauge fields. Basics of the Hosotani mechanism are reviewed, and applied to the electroweak theory. The Higgs boson mass and the Kaluza-Klein excitation scale are related to the weak W-boson mass.

hep-ph↗

arXiv2005

Higgs Boson Mass and Electroweak-Gravity Hierarchy from Dynamical Gauge-Higgs Unification in the Warped Spacetime

Dynamical electroweak symmetry breaking by the Hosotani mechanism in the Randall-Sundrum warped spacetime is examined, relations among the W-boson mass (m_W), the Kaluza-Klein mass scale (M_{KK}), and the Higgs boson mass (m_H) being derived. It is shown that M_{KK}/m_W = (2 pi kR)^{1/2} (pi/theta_W) and m_H /m_W = 0.058 kR (pi/theta_W), where k^2, R, and theta_W are the curvature and size of the extra-dimensional space and the Wilson line phase determined dynamically. For typical values kR = 12 and theta_W = (0.2 to 0.4) pi, one finds that M_{KK} = (1.7 to 3.5) TeV, k = (1.3 to 2.6) x 10^{19} GeV, and m_H = (140 to 280) GeV.

hep-ph↗

arXiv2004

Dynamical Gauge-Higgs Unification in the Electroweak Theory

$SU(2)_L$ doublet Higgs fields are unified with gauge fields in the $U(3)_s \times U(3)_w$ model of Antoniadis, Benakli and Quirós' on the orbifold $M^4 \times (T^2/Z_2)$. The effective potential for the Higgs fields (the Wilson line phases) is evaluated. The electroweak symmetry is dynamically broken to $U(1)_{EM}$ by the Hosotani mechanism. There appear light Higgs particles. There is a phase transition as the moduli parameter of the complex structure of $T^2$ is varied.

hep-ph↗

arXiv2004

Dynamical Gauge-Higgs Unification (SUSY04)

Dynamical gauge-Higgs unification is presented in higher dimensional gauge theory, in which both adjoint and fundamental Higgs fields are a part of gauge fields. Dynamical gauge symmetry breaking is induced through the Hosotani mechanism. Gauge theory, including the U(3) x U(3) model, is examined on M^4 x (T^2/Z_2).

hep-ph↗

arXiv2004

Dynamical Gauge-Higgs Unification

Gauge fields and both adjoint and fundamental Higgs fields are unified in gauge theory defined on an orbifold. It is shown how the Hosotani mechanism at the quantum level resolves the problem of the arbitrariness in boundary conditions imposed at the fixed points of the orbifold. The role of adjoint Higgs fields in the standard GUT, which are extra-dimensional components of gauge fields in the current scheme, is taken by the Hosotani mechanism and additional dynamics governing the selection of equivalence classes of boundary conditions. The roles of fundamental Higgs fields, namely those of inducing the electroweak symmetry breaking and giving masses to quarks and leptons, are taken by the Hosotani mechanism and by extra twists in boundary conditions for matter. SUSY scenario nicely fits this scheme. Explicit models are given for the gauge groups U(3) x U(3), SU(5), and SU(6) on the orbifolds M^4 x (S^1/Z_2) and M^4 x (T^2/Z_2).

hep-ph↗

arXiv2004

Dynamical Gauge Symmetry Breaking and Mass Generation on the Orbifold T^2/Z_2

Dynamical gauge symmetry breaking on the orbifold $T^2/Z_2$ is shown to occur through quantum dynamics of Wilson line phases. Different sets of boundary conditions on $T^2/Z_2$ can be related to each other by Wilson line phases, forming equivalence classes. The effective potential for Wilson line phases is evaluated at the one loop level in SU(2) gauge theory. Depending on the fermion content, the SU(2) symmetry can be broken either completely or partially to U(1) without introducing additional Higgs scalar fields. When SU(2) is completely broken, each of three components of the gauge fields may acquire a distinct mass. Masses are generated through the combination of $T^2$ twists and dynamics of Wilson line phases.

hep-ph↗

arXiv2004

Gravitating Fermionic Lumps with a False Vacuum Core

We investigate gravitating lumps with a false vacuum core surrounded by the true vacuum in a scalar field potential. Such configurations become possible in the Einstein gravity in the presence of fermions at the core. Gravitational interactions as well as Yukawa interactions are essential for such lumps to exist. The mass and size of gravitating lumps sensitively depend on the scale characterizing the scalar field potential and the density of fermions. These objects can exist in the universe at various scales.

gr-qc↗

arXiv2004

Classification and dynamics of equivalence classes in SU(N) gauge theory on the orbifold $S^1/Z_2$

The dynamical determination of the boundary conditions in SU(N) gauge theory on the orbifold $S^1/Z_2$ is investigated. We classify the equivalence classes of the boundary conditions, and then the vacuum energy density of the theory in each equivalence class is evaluated at one loop order. Unambiguous comparison of the vacuum energy densities in the two theories in different equivalence classes becomes possible in supersymmetric theories. It is found that in the supersymmetric SU(5) models with the Scherk-Schwarz supersymmetry breaking, the theory with the boundary conditions yielding the standard model symmetry is in the equivalence class with the lowest energy density, though the low energy theory is not identically the minimal supersymmetric standard model. We also study how particular boundary conditions are chosen in the cosmological evolution of the universe.

hep-ph↗

arXiv2004

False Vacuum Lumps with the Fermionic Core

Stable gravitating lumps with a false vacuum core surrounded by the true vacuum in a scalar field potential exist in the presence of fermions at the core. These objects may exist in the universe at various scales.

gr-qc↗

arXiv2004

Dynamical symmetry breaking in Gauge-Higgs unification on orbifold

We study the dynamical symmetry breaking in the gauge-Higgs unification of the 5D theory compactified on an orbifold, $S^1/Z_2$. This theory identifies Wilson line degrees of freedoms as ``Higgs doublets''. We consider $SU(3)_c \times SU(3)_W$ and SU(6) models with the compactification scale of order a few TeV. The gauge symmetries are reduced to $SU(3)_c \times SU(2)_L \times U(1)_Y$ and $SU(3)_c \times SU(2)_L \times U(1)_Y \times U(1)$, respectively, through the orbifolding boundary conditions. We estimate the one loop effective potential of ``Higgs doublets'', and find that the electro-weak breaking is realized through the radiative corrections when there are suitable numbers of bulk fields possessing the suitable representations. The masses of ``Higgs doublets'' are ${\mathcal O}(100)$ GeV in this scenario.

hep-ph↗

arXiv2003

Dynamical Rearrangement of Gauge Symmetry on the Orbifold S^1/Z_2

Gauge theory defined on the orbifold $M^4 \times (S^1/Z_2)$ is investigated from the viewpoint of the Hosotani mechanism. Rearrangement of gauge symmetry takes place due to the dynamics of Wilson line phases. The physical symmetry of the theory, in general, differs from the symmetry of the boundary conditions. Several sets of boundary conditions having distinct symmetry can be related by gauge transformations, belonging to the same equivalence class. The Hosotani mechanism guarantees the same physics in all theories in one equivalent class. Examples are presented in the SU(5) theory. Zero modes of the extra-dimensional components, $A_y$, of gauge fields acquire masses by radiative corrections. In the nonsupersymmetric SU(5) model the presence of bulk fermions leads to the spontaneous breaking of color SU(3). In the supersymmetric model with Scherk-Schwarz SUSY breaking zero modes of $A_y$'s acquire masses of order of the SUSY breaking.

hep-ph↗

arXiv2003

GUT ON ORBIFOLDS -- Dynamical Rearrangement of Gauge Symmetry --

Grand unified theory defined on higher-dimensional orbifolds provides a new way to solve the hierarchy problem. In gauge theory on an orbifold many different sets of boundary conditions imposed at orbifold fixed points (branes) are related by large gauge transformations, forming an equivalent class of boundary conditions. Thanks to the Hosotani mechanism the physics remains the same in all theories in a given equivalent class, though the symmetry of boundary conditions differs from each other. Quantum dynamics of Wilson line phases rearranges the gauge symmetry. In the nonsupersymmetric SU(5) model the presence of bulk fermions leads to the spontaneous breaking of color SU(3). In the supersymmetric model with Scherk-Schwarz SUSY breaking, color SU(3) is spontaneously broken even in the absence of bulk fermions if there are Higgs multiplets.

hep-ph↗

arXiv2002

Weyl Invariant Spacetime

A new class of Weyl invariant backgrounds are presented in terms of the metric $G_{μν}$ and the anti-symmetric Kalb-Ramond fields $B_{μν}$. The ten-dimensional spacetime is a product of four-dimensional flat spacetime and curved six-dimensional spacetime having nonvanishing Ricci tensors. The non-vanishing Kalb-Ramond field strengths cannot be written globally as $H=dB$, being of the monopole type. Nevertheless they define homogeneous spacetime with no singularity.

hep-th↗

arXiv2002

Cosmic Solutions in the Einstein-Weinberg-Salam Theory and the Generation of Large Electric and Magnetic Fields

In the SU(2)_L x U(1)_Y standard electroweak theory coupled with the Einstein gravity, new topological configurations naturally emerge, if the spatial section of the universe is globally a three-sphere (S^3) with a small radius. The SU(2)_L gauge fields wrap the space nontrivially, producing homogeneous but anisotropic space. As the universe expands, large electric and magnetic fields are produced. The electromagnetic field configuration is characterized by the Hopf map.

hep-ph↗

arXiv2002

Cosmology in the Einstein-Electroweak Theory and Magnetic Fields

In the SU(2)_{L} x U(1)_{Y} standard electroweak theory coupled with the Einstein gravity, new topological configurations naturally emerge, if the spatial section of the universe is globally a three-sphere(S^3) with a small radius. The SU(2)_L gauge fields and Higgs fields wrap the space nontrivially, residing at or near a local minimum of the potential. As the universe expands, however, the shape of the potential rapidly changes and the local minimum eventually disappears. The fields then start to roll down towards the absolute minimum. In the absence of the U(1)_Y gauge interaction the resulting space is a homogeneous and isotropic S^3, but the U(1)_Y gauge interaction necessarily induces anisotropy while preserving the homogeneity of the space. Large magnetic fields are generically produced over a substantial period of the rolling-over transition. The magnetic field configuration is characterized by the Hopf map.

hep-th↗

arXiv2001

Scaling Behavior in the Einstein-Yang-Mills Monopoles and Dyons

Scaling behavior in the moduli space of monopole and dyon solutions in the Einstein-Yang-Mills theory in the asymptotically anti-de Sitter space is derived. The mass of monopoles and dyons scales with respect to their magnetic and electric charges, independent of the values of the cosmological constant and gauge coupling constant. The stable monopole and dyon solutions are approximated by solutions in the fixed anti-de Sitter spacetime. Unstable solutions can be viewed as the Bartnik-McKinnon solutions dressed with monopole and dyon solutions in the fixed anti-de Sitter space.

gr-qc↗