10 research outputs found
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