arXiv subjects

Takahiro Kubota

Publications and source records attributed to Takahiro Kubota.

41 records · Page 3Linked to original sources

arXiv1997

Renormalization Group Flow near the Superconformal Points in N=2 Supersymmetric Gauge Theories

The behavior of the beta-function of the low-energy effective coupling in the N=2 supersymmetric SU(2) QCD with several massive matter hypermultiplets and in the SU(3) Yang-Mills theory is determined near the superconformal points in the moduli space. The renormalization group flow is unambiguously fixed by looking at limited types of deformation near the superconformal points. It is pointed out that the scaling dimension of the beta-function is controlled by the scaling behavior of moduli parameters and the relation between them is explicitly worked out. Our scaling dimensions of the beta-functions are consistent in part with the results obtained recently by Bilal and Ferrari in a different method for the SU(2) QCD.

hep-th↗

arXiv1996

Screening Theorem for the Higgs Decays into the Gauge Boson Pairs

The radiative corrections to the decays of the neutral CP-even Higgs boson $H$ into a longitudinal gauge boson pair, {\it i.e.}, $H \rightarrow Z_LZ_L$ and $W^+_LW^-_L$ are analyzed in the two Higgs doublet model by making use of the equivalence theorem. The sensitivity of the decay rates to the masses of the heavier Higgs bosons, charged $G^{\pm}$ and CP-odd neutral $A$ bosons as well as CP-even neutral $h$ boson, is investigated. Though the width $Γ(H \rightarrow Z_LZ_L)$ is insensitive to the masses of heavier Higgs bosons, $Γ(H \rightarrow W^+_LW^-_L)$ is sensitive and the radiative corrections are minimized for $m_G = m_A$. These results are explained completely on the basis of a new screening theorem for the vertices, which is closely connected with the custodial $SU(2)_V$ symmetry.

hep-ph↗

arXiv1995

Effective Topological Theory for Gravitational Anyon Scatterings at Ultra-High Energies

The idea of the effective topological theory for high-energy scattering proposed by H. and E. Verlinde is applied to the $(2+1)$ dimensional gravity with Einstein action plus Chern-Simons terms. The calculational steps in the topological description are compared with the eikonal approximation. It is shown that the Lagrangian of the effective topological theory turns out to vanish except for boundary terms.

hep-th↗

arXiv1994

Radiative Corrections to the Higgs Boson Decay into a Longitudinal $W$-Boson Pair in a Two-Doublet Model

The decay rate of a (neutral) Higgs boson ($H$) going into a longitudinal $W$-boson pair is calculated by including one loop radiative corrections in a two-Higgs doublet model. It is assumed that the Higgs boson $H$ is much heavier than the $W$ boson and a full use has been made of the equivalence theorem. A possibility is explored extensively that the precise measurement of the decay rate of $H$ could be useful as a probe of the other neutral as well as charged Higgs bosons through potentially important radiative corrections. It is pointed out that, for some choice of the parameters, the radiative corrections are sizable and that there exist a possibility of extracting useful information on the other Higgs boson masses.

hep-ph↗

arXiv1993

Twisting Toroidal Magnetic Fields and the Seasonal Oscillation of the Solar Neutrino Flux II

An intriguing possibility is explored that the solar neutrino data could be used as a probe to the magnetic field structure in the sun. Various cyclic phenomena occurring on the surface of the sun have been accounted for by the so-called dynamo-mechanism. According to this, a self-generating mechanism of solar cyclic activities gives rise to twisting toroidal magnetic fields in the convective zone. Although its magnitude is not known, the orientation of the twist is certainly opposite in northern and southern hemispheres of the sun. We show by numerical calculation that the solar neutrino flux, being sensitive to the twist, could exhibit observable seasonal oscillation, provided that the twist is sizable in magnitude and the neutrinos have reasonably large magnetic moments. This oscillation is ascribed to the fact that the earth's orbit is slightly inclined to the sun's equator, and that solar neutrinos pass through the northern (southern) hemisphere of the sun around September (March). We also argue that similar seasonal oscillation could be exhibited in the azimuthal asymmetry of recoiling electrons scattered by the solar neutrinos which are expected to be observed in the super-Kamiokande detector.

hep-ph↗