489,854 research outputs found
No-Scale Solution to Little Hierarchy
We show that the little hierarchy problem can be solved in the no-scale
supergravity framework. In this model the supersymmetry breaking scale is
generated when the electroweak symmetry breaking condition is satisfied and
therefore, unlike usual supersymmetric models, the correlation between the
electroweak symmetry breaking scale and the average stop mass scale can be
justified. This correlation solves the little hierarchy puzzle. Using minimal
supergravity boundary conditions, we find that the parameter space predicted by
no-scale supergravity is allowed by all possible experimental constraints. The
predicted values of supersymmetric particle masses are low enough to be very
easily accessible at the LHC. This parameter space will also be probed in the
upcoming results from the dark matter direct detection experiments.Comment: 15 pages, 2 figure
Bounds on Neutrino Mass in Viscous Cosmology
Effective field theory of dark matter fluid on large scales predicts the
presence of viscosity of the order of . It has been shown
that this magnitude of viscosities can resolve the discordance between large
scale structure observations and Planck CMB data in the -
and - parameters space. Massive neutrinos suppresses the
matter power spectrum on the small length scales similar to the viscosities. We
show that by including the effective viscosity, which arises from summing over
non linear perturbations at small length scales, severely constrains the
cosmological bound on neutrino masses. Under a joint analysis of Planck CMB and
different large scale observation data, we find that upper bound on the sum of
the neutrino masses at 2- level, decreases from eV (normal hierarchy) and eV (inverted
hierarchy) to eV (normal hierarchy) and eV (inverted hierarchy) when the effective viscosities are included.Comment: 19 pages, 13 figure
Log-Poisson Hierarchical Clustering of Cosmic Neutral Hydrogen and Ly-alpha Transmitted Flux of QSO Absorption Spectrum
we study, in this paper, the non-Gaussian features of the mass density field
of neutral hydrogen fluid and the Ly-alpha transmitted flux of QSO absorption
spectrum from the point-of-view of self-similar log-Poisson hierarchy. It has
been shown recently that, in the scale range from the onset of nonlinear
evolution to dissipation, the velocity and mass density fields of cosmic baryon
fluid are extremely well described by the She-Leveque's scaling formula, which
is due to the log-Poisson hierarchical cascade. Since the mass density ratio
between ionized hydrogen to total hydrogen is not uniform in space, the mass
density field of neutral hydrogen component is not given by a similar mapping
of total baryon fluid. Nevertheless, we show, with hydrodynamic simulation
samples of the concordance CDM universe, that the mass density field
of neutral hydrogen, is also well described by the log-Poisson hierarchy. We
then investigate the field of Ly transmitted flux of QSO absorption
spectrum. Due to redshift distortion, Ly transmitted flux fluctuations
are no longer to show all features of the log-Poisson hierarchy. However, some
non-Gaussian features predicted by the log-Poisson hierarchy are not affected
by the redshift distortion. We test these predictions with the high resolution
and high S/N data of quasars Ly absorption spectra. All results given
by real data, including -hierarchy, high order moments and scale-scale
correlation, are found to be well consistent with the log-Poisson hierarchy. We
compare the log-Poisson hierarchy with the popular log-normal model of the
Ly transmitted flux. The later is found to yield too strong
non-Gaussianity at high orders, while the log-Poisson hierarchy is in agreement
with observed data.Comment: 24 pages, 9 figures, accepted by Ap
de Sitter Thin Brane Model
We discuss the large mass hierarchy problem in a braneworld model which
represents our acceleratively expanding universe. The Randall-Sundrum (RS)
model with warped one extra dimension added to flat 4-dimensional space-time
cannot describe our expanding universe. Here, we study instead the de Sitter
thin brane model. This is described by the same action as that for the RS
model, but the 4-dimensional space-time on the branes is . We study
the model for both the cases of positive 5-dimensional cosmological constant
and negative one. In the positive case, the
4-dimensional large hierarchy necessitates a 5-dimensional large hierarchy, and
we cannot get a natural explanation. On the other hand, in the negative
case, the large hierarchy is naturally realized in the
5-dimensional theory in the same manner as in the RS model. Moreover, another
large hierarchy between the Hubble parameter and the Planck scale is realized
by the hierarchy of the 5-dimensional quantities. Finally,
we find that the lightest mass of the massive Kaluza-Klein modes and the
intervals of the mass spectrum are of order , which are the same
as in the RS case and do not depend on the value of the Hubble parameter.Comment: 24 pages, 6 figures. v5: published versio
Low-temperature dynamics of Long-Ranged Spin-Glasses : full hierarchy of relaxation times via real-space renormalization
We consider the long-ranged Ising spin-glass with random couplings decaying
as a power-law of the distance, in the region of parameters where the
spin-glass phase exists with a positive droplet exponent. For the Metropolis
single-spin-flip dynamics near zero temperature, we construct via real-space
renormalization the full hierarchy of relaxation times of the master equation
for any given realization of the random couplings. We then analyze the
probability distribution of dynamical barriers as a function of the spatial
scale. This real-space renormalization procedure represents a simple explicit
example of the droplet scaling theory, where the convergence towards local
equilibrium on larger and larger scales is governed by a strong hierarchy of
activated dynamical processes, with valleys within valleys.Comment: v2=final versio
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