Geodesic acoustic mode oscillation in the low frequency range

In order to understand the various appearances of geodesic acoustic modes (GAM) in experiments, the following specific problems are theoretically addressed: (1) The asymmetry of the potential field of GAMs, which is enhanced by the coupling with ion acoustic modes. It may affect GAMs in plasmas with electron temperatures higher than those of the ions. (2) The possible existence of GAMs in the lower frequency range: This is discussed in connection with the uniqueness of the kinetic response of the plasma to an external field associated with the geodesic curvature of the magnetic lines of force. (3) The extension of the theory to cover both tokamaks and helical systems: Differences between the helical-type and the tokamak-type GAMs are discussed in terms of their differences in connection length. In a device of mixed helicity, helical natured GAMs are predicted to appear depending on the intensity of the corresponding geodesic curvature and electron temperature

Orbifold Family Unification in SO(2N) Gauge Theory

We study the possibility of family unification on the basis of SO(2N) gauge theory on the five-dimensional space-time, $M^4\times S^1/Z_2$. Several SO(10), $SU(4) \times SU(2)_L \times SU(2)_R$ or SU(5) multiplets come from a single bulk multiplet of SO(2N) after the orbifold breaking. Other multiplets including brane fields are necessary to compose three families of quarks and leptons.Comment: 28 page

Orbifold Family Unification

We study the possibility of complete family unification in higher-dimensional space-time. Three families of matters in SU(5) grand unified theory are derived from a single bulk multiplet of SU(N) gauge group (N >= 9) in the framework of S^1/Z_2 orbifold models. In the case of the direct orbifold breaking down to the standard model gauge group, there are models in which bulk fields from a single multiplet and a few brane fields compose three families of quarks and leptons.Comment: Comments added, version to appear in Physical Review D (v3); References added (v2); 19 pages (v1

Gauge Mediation with D-term SUSY Breaking

We construct a gauge-mediation model with a D-term supersymmetry (SUSY) breaking. R-symmetry breaking necessary for generating the SUSY standard-model gaugino masses is given by gaugino condensation of a strongly coupled gauge theory in the hidden sector. The energy scale of the strong dynamics of the hidden sector gauge theory should be around the messenger mass scale M, or otherwise perturbative calculations would be reliable and would lead to negative soft mass squared for squarks and sleptons. Thus, all the mass scales are controlled by a virtually single parameter, \sqrt{D}/M. This model covers a very wide range of gravitino mass, m_{3/2} \simeq 1 eV--100 TeV. Possible embeddings of the model in string theory are also discussed.Comment: 15 pages; v2: comments and references adde

Product-Group Unification in Type IIB String Thoery

The product-group unification is a model of unified theories, in which masslessness of the two Higgs doublets and absence of dimension-five proton decay are guaranteed by a symmetry. It is based on SU(5) x U(N) (N=2,3) gauge group. It is known that various features of the model are explained naturally, when it is embedded in a brane world. This article describes an idea of how to accommodate all the particles of the model in Type IIB brane world. The GUT-breaking sector is realized by a D3--D7 system, and chiral quarks and leptons arise from intersection of D7-branes. The D-brane configuration can be a geometric realization of the non-parallel family structure of quarks and leptons, an idea proposed to explain the large mixing angles observed in the neutrino oscillation. The tri-linear interaction of the next-to-minimal supersymmetric standard model is obtained naturally in some cases.Comment: 33 pages, 5 figure