506 research outputs found
Observing Signals of the Bulk Matter RS Model through Rare Decays of SUSY Particles
The bulk matter Randall-Sundrum (RS) model is a setup where Standard Model
(SM) matter and gauge fields reside in the bulk of 5D warped spacetime while
the Higgs field is confined on the IR brane. The wavefunctions of the 1st and
2nd generation matter particles are localized towards the UV brane and those of
the 3rd generation towards the IR brane, so that the hierarchical structure of
the Yukawa couplings arises geometrically without hierarchy in fundamental
parameters. This paper discusses an experimental test of this model in the case
where the Kaluza-Klein scale is far above the collider scale, but the model is
combined with 5D Minimal SUSY Standard Model (MSSM) and SUSY particles are in
the reach of collider experiments. A general SUSY breaking mass spectrum
consistent with the bulk matter RS model is considered: SUSY breaking sector
locates on the IR brane and its effects are mediated to 5D MSSM through a
hybrid of gravity mediation, gaugino mediation and gauge mediation. This paper
argues that it is possible to observe the signals of the bulk matter RS model
through rare decays of "almost SU(2) singlet mass eigenstates" that are induced
by flavor-violating gravity mediation contributions to matter soft SUSY
breaking terms
A new measure of using the lensing dispersion in high- type Ia SNe
The gravitational lensing magnification or demagnification due to large-scale
structures induces a scatter in peak magnitudes of high redshift type Ia
supernovae (SNe Ia). The amplitude of the lensing dispersion strongly depends
on that of density fluctuations characterized by the parameter.
Therefore the value of is constrained by measuring the dispersion in
the peak magnitudes. We examine how well SN Ia data will provide a constraint
on the value of using a likelihood analysis method. It is found that
the number and quality of SN Ia data needed for placing a useful constraint on
is attainable with Next Generation Space Telescope.Comment: 9 pages, 3 figures. Accepted for publication in The Astrophysical
Journa
Detection of Dark Matter Concentrations in the Field of Cl 1604+4304 from Weak Lensing Analysis
We present a weak-lensing analysis of a region around the galaxy cluster Cl
1604+4304 (z=0.897) on the basis of the deep observations with the HST/WFPC2.
We apply a variant of Schneider's aperture mass technique to the observed WFPC2
field and obtain the distribution of weak-lensing signal-to-noise (S/N) ratio
within the field. The resulting S/N map reveals a clear pronounced peak located
about 1.7 arcmin (850h_{50}^{-1} kpc at z=0.897) southwest of the second peak
associated with the optical cluster center determined from the dynamical
analysis of Postman et al. A non-linear finite-field inversion method has been
used to reconstruct the projected mass distribution from the observed shear
field. The reconstructed mass map shows a super-critical feature at the
location of the S/N peak as well as in the cluster central region. Assuming the
redshift distribution of field galaxies, we obtain the total mass in the
observed field to be 1.0 h_{50}^{-1} 10^{15} M_sun for =1.0. The estimated
mass within a circular aperture of radius 280h_{50}^{-1} kpc centered on the
dark clump is 2.4h_{50}^{-1} 10^{14} M_sun. We have confirmed the existence of
the ` dark ' mass concentration from another deep HST observation with a
slightly different ~20 arcsec pointing.Comment: 7 pages, 3 figure
Minimal Flavor Violation in the Minimal U(1)_{B-L} Model and Resonant Leptogenesis
We investigate the resonant leptogenesis scenario in the minimally
extended standard model with minimal flavor violation. In our
model, the gauge symmetry is broken at the TeV scale and standard
model singlet neutrinos gain Majorana masses of order TeV. In addition, we
introduce a flavor symmetry on the singlet neutrinos at a scale higher than
TeV. The flavor symmetry is explicitly broken by the neutrino Dirac Yukawa
coupling, which induces splittings in the singlet neutrino Majorana masses at
lower scales through renormalization group evolutions. We call this setup
"minimal flavor violation". The mass-splittings are proportional to the tiny
Dirac Yukawa coupling, and hence they automatically enhance the CP asymmetry
parameter necessary for the resonant leptogenesis mechanism. In this paper, we
calculate the baryon number yield by solving the Boltzmann equations, including
the effects of gauge boson that also has TeV scale mass and causes
washing-out of the singlet neutrinos in the course of thermal leptogenesis. The
Dirac Yukawa coupling for neutrinos is fixed in terms of neutrino oscillation
data and an arbitrary complex-valued orthogonal matrix. We show
that the right amount of baryon number asymmetry can be achieved through
thermal leptogenesis in the context of the minimal flavor violation with
singlet neutrinos and gauge boson at the TeV scale. These
particles can be discovered at the LHC in the near future
Nonexponential decay of an unstable quantum system: Small--value s-wave decay
We study the decay process of an unstable quantum system, especially the
deviation from the exponential decay law. We show that the exponential period
no longer exists in the case of the s-wave decay with small value, where
the value is the difference between the energy of the initially prepared
state and the minimum energy of the continuous eigenstates in the system. We
also derive the quantitative condition that this kind of decay process takes
place and discuss what kind of system is suitable to observe the decay.Comment: 17 pages, 6 figure
Equation of motion for relativistic compact binaries with the strong field point particle limit : Formulation, the first post-Newtonian and multipole terms
We derive the equation of motion for the relativistic compact binaries in the
post-Newtonian approximation taking explicitly their strong internal gravity
into account. For this purpose we adopt the method of the point particle limit
where the equation of motion is expressed in terms of the surface integrals. We
examine carefully the behavior of the surface integrals in the derivation. As a
result, we obtain the Einstein-Infeld-Hoffman equation of motion at the first
post-Newtonian (1PN) order, and a part of the 2PN order which depends on the
quadrupole moments and the spins of component stars. Hence, it is found that
the equation of motion in the post-Newtonian approximation is valid for the
compact binaries by a suitable definition of the mass, spin and quadrupole
moment.Comment: revised version. 27pages, three tables, revtex. Some errors have been
corrected and some explanations have been adde
R-mode Instability of Slowly Rotating Non-isentropic Relativistic Stars
We investigate properties of -mode instability in slowly rotating
relativistic polytropes. Inside the star slow rotation and low frequency
formalism that was mainly developed by Kojima is employed to study axial
oscillations restored by Coriolis force. At the stellar surface, in order to
take account of gravitational radiation reaction effect, we use a near-zone
boundary condition instead of the usually imposed boundary condition for
asymptotically flat spacetime. Due to the boundary condition, complex
frequencies whose imaginary part represents secular instability are obtained
for discrete -mode oscillations in some polytropic models. It is found that
such discrete -mode solutions can be obtained only for some restricted
polytropic models. Basic properties of the solutions are similar to those
obtained by imposing the boundary condition for asymptotically flat spacetime.
Our results suggest that existence of a continuous part of spectrum cannot be
avoided even when its frequency becomes complex due to the emission of
gravitational radiation.Comment: 10 pages, 4 figures, accepted for publlication in PR
How is the local-scale gravitational instability influenced by the surrounding large-scale structure formation?
We develop the formalism to investigate the relation between the evolution of
the large-scale (quasi) linear structure and that of the small-scale nonlinear
structure in Newtonian cosmology within the Lagrangian framework. In doing so,
we first derive the standard Friedmann expansion law using the averaging
procedure over the present horizon scale. Then the large-scale (quasi) linear
flow is defined by averaging the full trajectory field over a large-scale
domain, but much smaller than the horizon scale. The rest of the full
trajectory field is supposed to describe small-scale nonlinear dynamics. We
obtain the evolution equations for the large-scale and small-scale parts of the
trajectory field. These are coupled to each other in most general situations.
It is shown that if the shear deformation of fluid elements is ignored in the
averaged large-scale dynamics, the small-scale dynamics is described by
Newtonian dynamics in an effective Friedmann-Robertson-Walker (FRW) background
with a local scale factor. The local scale factor is defined by the sum of the
global scale factor and the expansion deformation of the averaged large-scale
displacement field. This means that the evolution of small-scale fluctuations
is influenced by the surrounding large-scale structure through the modification
of FRW scale factor. The effect might play an important role in the structure
formation scenario. Furthermore, it is argued that the so-called {\it
optimized} or {\it truncated} Lagrangian perturbation theory is a good
approximation in investigating the large-scale structure formation up to the
quasi nonlinear regime, even when the small-scale fluctuations are in the
non-linear regime.Comment: 15pages, Accepted for publication in Gravitation and General
Relativit
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