arXiv subjects

K. -I. Izawa

Publications and source records attributed to K. -I. Izawa.

At least 37 records · Page 2Linked to original sources

arXiv2004

Dimensional Reduction of Nonlinear Gauge Theories

We investigate an extension of 2D nonlinear gauge theory from the Poisson sigma model based on Lie algebroid to a model with additional two-form gauge fields. Dimensional reduction of 3D nonlinear gauge theory yields an example of such a model, which provides a realization of Courant algebroid by 2D nonlinear gauge theory. We see that the reduction of the base structure generically results in a modification of the target (algebroid) structure.

hep-th↗

arXiv2004

Realization of Minimal Supergravity

Minimal supergravity mediation of supersymmetry breaking has attracted much attention due to its simplicity, which leads to its predictive power. We consider how Nature possibly realizes minimal supergravity through inflationary selection of the theory. Minimality is impressively consistent with the present observational bounds and it might be tested with the aid of low-energy soft parameters obtained in future experiments.

hep-ph↗

arXiv2004

Super- and CP-symmetric QCD in Higher Dimensions

An extremely precise global symmetry is necessary in the Peccei--Quinn solution to the strong CP problem. Such symmetry arises when colored chiral fermions are localized in an internal space. We present a supersymmetric model that incorporates the above mechanism. Extra colored chiral multiplets around the supersymmetry-breaking scale are a generic prediction of the supersymetric model.

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arXiv2003

Supergravity Minimal Inflation and its Spectral Index Revisited

Natural supergravity models of new inflation are reconsidered as minimal inflationary models within slow-roll approximation. Their running spectral index is derived in a revised form with recent observational results and future refinements in mind. This will possibly determine essential model parameters with respect to Planck-suppressed operators.

hep-ph↗

arXiv2003

Warped QCD without the Strong CP Problem

QCD in a five-dimensional sliced AdS bulk with chiral extra-quarks on the boundaries is generically free from the strong CP problem. Accidental axial symmetry is naturally present except for suppressed breaking interactions, which plays a role of the Peccei-Quinn symmetry to make the strong CP phase sufficiently small. Breaking suppression and enhancement due to AdS warping are considered in addition to naive boundary separation effects.

hep-ph↗

arXiv2002

Higher-Dimensional QCD without the Strong CP Problem

QCD in a five-dimensional sliced bulk with chiral extra-quarks on the boundaries is generically free from the strong CP problem. Accidental axial symmetry is naturally present except for suppressed breaking interactions, which plays a role of the Peccei-Quinn symmetry to make the strong CP phase sufficiently small.

hep-ph↗

arXiv2002

R-Invariant Unification with Dynamical Higgs Multiplets

We construct R-invariant grand unification models with composite Higgs multiplets. Higgs doublets are massless due to the R symmetry, which is not spontaneously broken at the unification scale, while Higgs triplets get large masses from a dynamically generated superpotential, which is allowed by an R anomaly.

hep-ph↗

arXiv2001

Tubular Field Theory

We propose tubular field theory, which is a continuum analogue of lattice field theory. One-dimensional links (and zero-dimensional sites) in lattice field theory are replaced by two-dimensional tubes to result in two-dimensional spacetime microscopically. As an example, scalar and gauge fields are considered in `three-dimensional' tubular spacetime.

hep-th↗

arXiv2001

Warped Compactification with a Four-Brane

Warped compactification of the six-dimensional bulk with a negative cosmological constant is realized with a 4-brane along with an abelian gauge theory. No fine tuning of couplings are needed to obtain the vanishing cosmological constant in four dimensions, as is the case for the bulk with a positive cosmological constant.

hep-th↗

arXiv2000

Quintessential Vanishing of the Cosmological Constant

We consider an effective field theory description of gravity coupled to a scalar field with volume-preserving diffeomorphism and Weyl invariances. The smallness of the cosmological constant is achieved when the potential of the scalar is extremely flat. This implies a possible relationship between the smallness and the quintessential sector of the cosmological constant.

hep-ph↗

arXiv2000

Quintessential Brane and the Cosmological Constant

We consider a quintessential sector realized on a hidden brane with a tiny warp factor, which implies a small value of the effective four-dimensional cosmological constant through an equation of motion for the quintessential scalar.

hep-ph↗

arXiv2000

Warped Compactification with an Abelian Gauge Theory

We investigate warped compactification with an abelian gauge theory in six dimensions. The vanishing cosmological constant in four dimensions can generically be realized with a regular metric even in a 3-brane background without fine tuning of couplings.

hep-th↗

arXiv1999

On Nonlinear Gauge Theory from a Deformation Theory Perspective

Nonlinear gauge theory is a gauge theory based on a nonlinear Lie algebra (finite W algebra) or a Poisson algebra, which yields a canonical star product for deformation quantization as a correlator on a disk. We pursue nontrivial deformation of topological gauge theory with conjugate scalars in two dimensions. This leads to two-dimensional nonlinear gauge theory exclusively, which implies its essential uniqueness. We also consider a possible extension to higher dimensions.

hep-th↗

arXiv1999

Grand-Unification Scale Generation through the Anomalous U(1) Breaking

We discuss the anomalous U(1) gauge symmetry as a mechanism of generating the grand-unification scale. We conclude that unification to a simple group cannot be realized unless some parameters are ``tuned'', and that models with product gauge groups are preferred. We consider the ``R-invariant natural unification'' model with gauge groups SU(5)_{GUT} \times U(3)_H. In this model the doublet-triplet splitting problem is solved and the unwanted GUT relation m_s = m_μis avoided maintaining m_b = m_τ. Moreover, R-invariance suppresses the dangerous proton decays induced by dimension four and five operators.

hep-ph↗

arXiv1999

Long-Lived Superheavy Particles in Dynamical Supersymmetry-Breaking Models in Supergravity

Superheavy particles of masses $\simeq 10^{13}-10^{14} GeV$ with lifetimes $\simeq 10^{10}-10^{22} years$ are very interesting, since their decays may account for the ultra-high energy (UHE) cosmic rays discovered beyond the Greisen-Zatsepin-Kuzmin cut-off energy $E \sim 5 \times 10^{10} GeV$. We show that the presence of such long-lived superheavy particles is a generic prediction of QCD-like SU(N_c) gauge theories with N_f flavors of quarks and antiquarks and the large number of colors N_c. We construct explicit models based on supersymmetric SU(N_c) gauge theories and show that if the dynamical scale $Λ\simeq 10^{13}-10^{14} GeV$ and N_c = 6-10 the lightest composite baryons have the desired masses and lifetimes to explain the UHE cosmic rays. Interesting is that in these models the gaugino condensation necessarily occurs and hence these models may play a role of so-called hidden sector for supersymmetry breaking in supergravity.

hep-ph↗

arXiv1999

Cosmological Constants as Messenger between Branes

We present a supersymmetry-breaking scenario in which both the breaking in the hidden sector with no-scale type supergravity and that in the observable sector with gauge mediation are taken into account. The breaking scales in the hidden and observable sectors are related through the vanishing condition of the cosmological constant with a brane-world picture in mind. Suppressing flavor-changing neutral currents, we can naturally obtain the gravitino, Higgs(ino), and soft masses of the electroweak scale.

hep-ph↗

arXiv1999

Dynamical Inflation and Vacuum Selection

We consider an inflationary scenario where the energy scale of inflation stems from gauge theory dynamics. We point out its generic implications on vacuum selection of our universe, in particular, on determination of spacetime symmetries including its dimensions.

hep-ph↗

arXiv1999

A Gauge-Mediation Model of Dynamical SUSY Breaking with a Wide Range of the Gravitino Mass

We provide a gauge-mediation model of dynamical supersymmetry breaking where the gravitino mass takes a value in a wide range from 0.1 eV to 10 GeV. The lower mass region of order 100 keV or less deserves experimental and cosmological interests. The vacuum of our model is a true one without runaway instability, which may be desirable in a cosmological evolution of the universe.

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