126 research outputs found
Inflation and Gauge Hierarchy in Randall-Sundrum Compactification
We obtain the general inflationary solutions for the slab of five-dimensional
AdS spacetime where the fifth dimension is an orbifold and two
three-branes reside at its boundaries, of which the Randall-Sundrum model
corresponds to the static limit. The investigation of the general solutions and
their static limit reveals that the RS model recasts both the cosmological
constant problem and the gauge hierarchy problem into the balancing problem of
the bulk and the brane cosmological constants.Comment: 9 pages, revtex, minor changes and more references adde
Quark Mass Textures and sin 2 beta
Recent precise measurements of sin 2 beta from the B-factories (BABAR and
BELLE) and a better known strange quark mass from lattice QCD make precision
tests of predictive texture models possible. The models tested include those
hierarchical N-zero textures classified by Ramond, Roberts and Ross, as well as
any other hierarchical matrix Ansatz with non-zero 12 = 21 and vanishing 11 and
13 elements. We calculate the maximally allowed value for sin 2 beta in these
models and show that all the aforementioned models with vanishing 11 and 13
elements are ruled out at the 3 sigma level. While at present sin 2 beta and
|Vub/Vcb| are equally good for testing N-zero texture models, in the near
future the former will surpass the latter in constraining power.Comment: 1+20 pages, 2 figures, JHEP3 clas
Mixed Bino-Wino-Higgsino Dark Matter in Gauge Messenger Models
Almost degenerate bino and wino masses at the weak scale is one of unique
features of gauge messenger models. The lightest neutralino is a mixture of
bino, wino and higgsino and can produce the correct amount of the dark matter
density if it is the lightest supersymmetric particle. Furthermore, as a result
of squeezed spectrum of superpartners which is typical for gauge messenger
models, various co-annihilation and resonance regions overlap and very often
the correct amount of the neutralino relic density is generated as an interplay
of several processes. This feature makes the explanation of the observed amount
of the dark matter density much less sensitive to fundamental parameters. We
calculate the neutralino relic density assuming thermal history and present
both spin independent and spin dependent cross sections for the direct
detection. We also discuss phenomenological constraints from b to s gamma and
muon g-2 and compare results of gauge messenger models to well known results of
the mSUGRA scenario.Comment: 27 pages, 9 figures, references added, version to appear at JCA
Dynamical solution to the problem at TeV scale
We introduce a new confining force (\mu-color) at TeV scale to dynamically
generate a supersymmetry preserving mass scale which would replace the \mu
parameter in the minimal supersymmetric standard model (MSSM). We discuss the
Higgs phenomenology and also the pattern of soft supersymmetry breaking
parameters allowing the correct electroweak symmetry breaking within the
\mu-color model, which have quite distinctive features from the MSSM and also
from other generalizations of the MSSM.Comment: 12 pages, REVte
A criterion for admissible singularities in brane world
When gravity couples to scalar fields in Anti-de Sitter space, the geometry
becomes non-AdS and develops singularities generally. We propose a criterion
that the singularity is physically admissible if the integral of the on-shell
Lagrangian density over the finite range is finite everywhere. For all classes
of the singularities studied here, the criterion suggested in this paper
coincides with an independent proposal made by Gubser that the potential should
be bounded from above in the solution. This gives a reason why Gubser's
conjecture works.Comment: 14 pages, revtex, 1 table, references added, two other criteria
include
Natural Supersymmetry at the LHC
If the minimal supersymmetric standard model is the solution to the hierarchy
problem, the scalar top quark (stop) and the Higgsino should weigh around the
electroweak scale such as 200 GeV. A low messenger scale, which results in a
light gravitino, is also suggested to suppress the quantum corrections to the
Higgs mass parameters. Therefore the minimal model for natural supersymmetry is
a system with stop/Higgsino/gravitino whereas other superparticles are heavy.
We study the LHC signatures of the minimal system and discuss the discovery
potential and methods for the mass measurements.Comment: 19 pages, 6 figures, 1 tabl
Small Instanton Contribution to the Axion Potential in Supersymmetric Models
Small size QCD instantons may spoil the axion solution to the strong CP
problem if QCD is not asymptotically free at high energy scales. We examine
this issue in supersymmetric models using a manifestly supersymmetric scheme to
compute the axion potential induced by small size instantons. Applying this
scheme for a class of illustrative models, it is found that the resulting high
energy axion potential is highly model-dependent, but suppressed by more powers
of the soft supersymmetry breaking parameters and/or of the other small mass
scales than what is expected based on a naive instanton graph analysis. Our
analysis suggests that the axion solution is stable against the small QCD
instanton effects in a wide class of supersymmetric models even when QCD is not
asymtotically free at high energy scales.Comment: revtex, 19 pages, 2 table
The Far-Infrared Surveyor (FIS) for AKARI
The Far-Infrared Surveyor (FIS) is one of two focal plane instruments on the
AKARI satellite. FIS has four photometric bands at 65, 90, 140, and 160 um, and
uses two kinds of array detectors. The FIS arrays and optics are designed to
sweep the sky with high spatial resolution and redundancy. The actual scan
width is more than eight arcmin, and the pixel pitch is matches the diffraction
limit of the telescope. Derived point spread functions (PSFs) from observations
of asteroids are similar to the optical model. Significant excesses, however,
are clearly seen around tails of the PSFs, whose contributions are about 30% of
the total power. All FIS functions are operating well in orbit, and its
performance meets the laboratory characterizations, except for the two longer
wavelength bands, which are not performing as well as characterized.
Furthermore, the FIS has a spectroscopic capability using a Fourier transform
spectrometer (FTS). Because the FTS takes advantage of the optics and detectors
of the photometer, it can simultaneously make a spectral map. This paper
summarizes the in-flight technical and operational performance of the FIS.Comment: 23 pages, 10 figures, and 2 tables. Accepted for publication in the
AKARI special issue of the Publications of the Astronomical Society of Japa
Simplified Models for LHC New Physics Searches
This document proposes a collection of simplified models relevant to the
design of new-physics searches at the LHC and the characterization of their
results. Both ATLAS and CMS have already presented some results in terms of
simplified models, and we encourage them to continue and expand this effort,
which supplements both signature-based results and benchmark model
interpretations. A simplified model is defined by an effective Lagrangian
describing the interactions of a small number of new particles. Simplified
models can equally well be described by a small number of masses and
cross-sections. These parameters are directly related to collider physics
observables, making simplified models a particularly effective framework for
evaluating searches and a useful starting point for characterizing positive
signals of new physics. This document serves as an official summary of the
results from the "Topologies for Early LHC Searches" workshop, held at SLAC in
September of 2010, the purpose of which was to develop a set of representative
models that can be used to cover all relevant phase space in experimental
searches. Particular emphasis is placed on searches relevant for the first
~50-500 pb-1 of data and those motivated by supersymmetric models. This note
largely summarizes material posted at http://lhcnewphysics.org/, which includes
simplified model definitions, Monte Carlo material, and supporting contacts
within the theory community. We also comment on future developments that may be
useful as more data is gathered and analyzed by the experiments.Comment: 40 pages, 2 figures. This document is the official summary of results
from "Topologies for Early LHC Searches" workshop (SLAC, September 2010).
Supplementary material can be found at http://lhcnewphysics.or
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