3,739 research outputs found
Dynamical GUT breaking and mu-term driven supersymmetry breaking
Models for dynamical breaking of supersymmetric grand unified theories are
presented. The doublet-triplet splitting problem is absent since the Higgs
doublet superfields can be identified with the massless mesons of the strong
gauge group whereas there are no massless states corresponding to the colored
Higgs fields. Various strong gauge groups SU(Nc), Sp(Nc) and SO(Nc) are
examined. In a model with SO(9) strong gauge group, adding the mu-term for the
Higgs fields triggers to break supersymmetry in a meta-stable vacuum. The
pattern of the supersymmetry breaking parameters is predicted to be the
gauge-mediation type with modifications in the Higgs sector.Comment: 23 pages, 1 figure; version to appear in PR
Making confining strings out of mesons
The light mesons such as pi, rho, omega, f0, and a0 are possible candidates
of magnetic degrees of freedom, if a magnetic dual picture of QCD exists. We
construct a linear sigma model to describe spontaneous breaking of the magnetic
gauge group, in which there is a stable vortex configuration of vector and
scalar mesons. We numerically examine whether such a string can be interpreted
as the confining string. By using meson masses and couplings as inputs, we
calculate the tension of the string as well as the strength of the Coulomb
force between static quarks. They are found to be consistent with those
inferred from the quarkonium spectrum and the Regge trajectories of hadrons. By
using the same Lagrangian, the critical temperature of the QCD phase transition
is estimated, and a non-trivial flavor dependence is predicted. We also discuss
a possible connection between the Seiberg duality and the magnetic model we
studied.Comment: 22 pages, 2 figures, 3 tables, typos corrected, references adde
Direct Mediation of Meta-Stable Supersymmetry Breaking
The supersymmetric SU(Nc) Yang-Mills theory coupled to Nf matter fields in
the fundamental representation has meta-stable vacua with broken supersymmetry
when Nc < Nf < 3/2 Nc. By gauging the flavor symmetry, this model can be
coupled directly to the standard model. We show that it is possible to make a
slight deformation to the model so that gaugino masses are generated and the
Landau pole problem can be avoided. The deformed model has simple realizations
on intersecting branes in string theory, where various features of the
meta-stable vacua are encoded geometrically as brane configurations.Comment: 22 pages, 4 figures, a reference added, version to appear in PR
Sex Differences in Recombination in Sticklebacks.
Recombination often differs markedly between males and females. Here we present the first analysis of sex-specific recombination in Gasterosteus sticklebacks. Using whole-genome sequencing of 15 crosses between G. aculeatus and G. nipponicus, we localized 698 crossovers with a median resolution of 2.3 kb. We also used a bioinformatic approach to infer historical sex-averaged recombination patterns for both species. Recombination is greater in females than males on all chromosomes, and overall map length is 1.64 times longer in females. The locations of crossovers differ strikingly between sexes. Crossovers cluster toward chromosome ends in males, but are distributed more evenly across chromosomes in females. Suppression of recombination near the centromeres in males causes crossovers to cluster at the ends of long arms in acrocentric chromosomes, and greatly reduces crossing over on short arms. The effect of centromeres on recombination is much weaker in females. Genomic differentiation between G. aculeatus and G. nipponicus is strongly correlated with recombination rate, and patterns of differentiation along chromosomes are strongly influenced by male-specific telomere and centromere effects. We found no evidence for fine-scale correlations between recombination and local gene content in either sex. We discuss hypotheses for the origin of sexual dimorphism in recombination and its consequences for sexually antagonistic selection and sex chromosome evolution
Geometry of One-Dimensional Wave Propagation
We investigate the geometrical features of one-dimensional wave propagation,
whose dynamics is described by the (2+1)-dimensional Lorentz group. We find
many interesting geometrical ingredients such as spinorlike behavior of wave
amplitudes, gauge transformations, Bloch-type equations, and Lorentz-group
Berry phases. We also propose an optical experiment to verify these effects.Comment: RevTeX, 16 pages, 6 postscript figure
Non-minimal Gauge Mediation and Moduli Stabilization
In this paper we consider U(1)-gauged Polony'i model with two spurions
coupled to a twisted closed string modulus. This offers a consistent setup for
metastable SUSY breakdown which allows for moduli stabilization and naturally
leads to gauge or hybrid gauge/gravitational mediation mechanism. Due to the
presence of the second spurion one can arrange for a solution of the \mu and
B_\mu problems in a version of modified Giudice-Masiero mechanism, which works
both in the limit of pure gauge mediation and in the mixed regime of hybrid
mediation.Comment: 12 pages, Discussion extended to include the effects of the gauge
boson exchange. This should be version 2
Mathematical structure of unit systems
We investigate the mathematical structure of unit systems and the relations
between them. Looking over the entire set of unit systems, we can find a
mathematical structure that is called preorder (or quasi-order). For some pair
of unit systems, there exists a relation of preorder such that one unit system
is transferable to the other unit system. The transfer (or conversion) is
possible only when all of the quantities distinguishable in the latter system
are always distinguishable in the former system. By utilizing this structure,
we can systematically compare the representations in different unit systems.
Especially, the equivalence class of unit systems (EUS) plays an important role
because the representations of physical quantities and equations are of the
same form in unit systems belonging to an EUS. The dimension of quantities is
uniquely defined in each EUS. The EUS's form a partially ordered set. Using
these mathematical structures, unit systems and EUS's are systematically
classified and organized as a hierarchical tree.Comment: 27 pages, 3 figure
Suppression of the charge-density-wave state in Sr_14Cu_24O_41 by calcium doping
The charge response in the spin chain/ladder compound Sr_14-xCa_xCu_24O_41 is
characterized by DC resistivity, low-frequency dielectric spectroscopy and
optical spectroscopy. We identify a phase transition below which a
charge-density wave (CDW) develops in the ladder arrays. Calcium doping
suppresses this phase with the transition temperature decreasing from 210 K for
x=0 to 10 K for x=9, and the CDW gap from 130 meV down to 3 meV, respectively.
This suppression is due to the worsened nesting originating from the increase
of the inter-ladder tight-binding hopping integrals, as well as from disorder
introduced at the Sr sites. These results altogether speak in favor of
two-dimensional superconductivity under pressure.Comment: 4 pages, 4 figures, accepted for publication in PR
Gravitational Baryogenesis
We show that a gravitational interaction between the derivative of the Ricci
scalar curvature and the baryon-number current dynamically breaks CPT in an
expanding universe and, combined with baryon-number-violating interactions, can
drive the universe towards an equilibrium baryon asymmetry that is
observationally acceptable.Comment: Revtex4, 4 pages, two figure
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