11,503 research outputs found
Non-Gaussianity in the HILC foreground-reduced three-year WMAP CMB map
A detection or nondetection of primordial non-Gaussianity in the CMB data is
essential not only to test alternative models of the physics of the early
universe but also to discriminate among classes of inflationary models. Given
this far reaching consequences of such a non-Gaussianity detection for our
understanding of the physics of the early universe, it is important to employ
alternative indicators in order to have further information about the
Gaussianity features of CMB that may be helpful for identifying their origins.
In this way, a considerable effort has recently gone into the design of
non-Gaussianity indicators, and in their application in the search for
deviation from Gaussianity in the CMB data. Recently we have proposed two new
large-angle non-Gaussianity indicators which provide measures of the departure
from Gaussianity on large angular scales. We have used these indicators to
carry out analyses of Gaussianity of the single frequency bands and of the
available foreground-reduced {\it five-year} maps with and without the KQ75
mask. Here we extend and complement these studies by performing a new analysis
of deviation from Gaussianity of the {\it three-year} harmonic ILC (HILC)
foreground-reduced full-sky and KQ75 masked maps obtained from WMAP data. We
show that this full-sky foreground-reduced maps presents a significant
deviation from Gaussianity, which is brought down to a level of consistency
with Gaussianity when the KQ75 mask is employed.Comment: 6 pages, 1 figure. To appear in IJMPD (2010). V2: Corrected ref.[8]
Absence of jump discontinuity in the magnetization in quasi-one-dimensional random-field Ising models
We consider the zero-temperature random-field Ising model in the presence of
an external field, on ladders and in one dimension with finite range
interactions, for unbounded continuous distributions of random fields, and show
that there is no jump discontinuity in the magnetizations for any quasi-one
dimensional model. We show that the evolution of the system at an external
field can be described by a stochastic matrix and the magnetization can be
obtained using the eigenvector of the matrix corresponding to the eigenvalue
one, which is continuous and differentiable function of the external field.Comment: 4 pages, 5 ps figures. Minor correction
Towards the robustness of the Affleck-Dine baryogenesis
We study the Affleck-Dine mechanism with various types of the Kahler
potential, and investigate whether or not the Affleck-Dine field could acquire
a large VEV as an initial condition for successful baryogenesis. In addition to
a negative Hubble-induced mass term, we find that large enough Hubble-induced
A-terms could also develop the minimum at large amplitude of the field.
Therefore, the Affleck-Dine mechanism works for broader classes of the
theories.Comment: 6 page
Non-Gaussianity from Baryon Asymmetry
We study a scenario that large non-Gaussianity arises from the baryon
asymmetry of the Universe. There are baryogenesis scenarios containing a light
scalar field, which may result in baryonic isocurvature perturbations with some
amount of non-Gaussianity. As an explicit example we consider the Affleck-Dine
mechanism and show that a flat direction of the supersymmeteric standard model
can generate large non-Gaussianity in the curvature perturbations, satisfying
the observational constraints on the baryonic isocurvature perturbations. The
sign of a non-linearity parameter, f_{NL}, is negative, if the Affleck-Dine
mechanism accounts for the observed baryon asymmetry; otherwise it can be
either positive or negative.Comment: 25 pages, 7 figures; minor correction, references added; version to
appear in JCA
Solving Cosmological Problems of Supersymmetric Axion Models in an Inflationary Universe
We revisit inflationary cosmology of axion models in the light of recent
developments on the inflaton decay in supergravity. We find that all the
cosmological difficulties, including gravitino, axino overproduction and
axionic isocurvature fluctuation, can be avoided if the saxion field has large
initial amplitude during inflation and decays before big-bang nucleosynthesis.Comment: 19 pages, 4 figure
Inhomogeneous baryogenesis, cosmic antimatter, and dark matter
A model of inhomogeneous baryogenesis based on the Affleck and Dine mechanism
is described. A simple coupling of the scalar baryon field to the inflaton
allows for formation of astronomically significant bubbles with a large baryon
(or antibaryon) asymmetry. During the farther evolution these domains form
compact stellar-like objects, or lower density clouds, or primordial black
holes of different size. According to the scenario, such high baryonic number
objects occupy relatively small fraction of space but despite that they may
significantly contribute to the cosmological mass density. For some values of
parameters the model allows the possibility the whole dark matter in the
universe to be baryonic. Furthermore, the model allows the existence of the
antibaryonic B-bubbles, i.e. a significant fraction of the mass density in the
universe can be in the form of the compact antimatter objects (e.g.
anti-stars).Comment: 31 pages, 5 figures, three references are adde
Mode coupling theory in the FDR-preserving field theory of interacting Brownian particles
We develop a renormalized perturbation theory for the dynamics of interacting
Brownian particles, which preserves the fluctuation-dissipation relation order
by order. We then show that the resulting one-loop theory gives a closed
equation for the density correlation function, which is identical with that in
the standard mode coupling theory.Comment: version to be published in Fast Track Communication in Journal of
Physics A:Math. Theo
Non-equilibrium critical behavior : An extended irreversible thermodynamics approach
Critical phenomena in non-equilibrium systems have been studied by means of a
wide variety of theoretical and experimental approaches. Mode-coupling,
renormalization group, complex Lie algebras and diagrammatic techniques are
some of the usual theoretical tools. Experimental studies include light and
inelastic neutron scattering, X-ray photon correlation spectroscopy, microwave
interferometry and several other techniques. Nevertheless no conclusive
reatment has been developed from the basic principles of a thermodynamic theory
of irreversible processes. We have developed a formalism in which we obtain
correlation functions as field averages of the associated functions. By
applying such formalism we attempt to find out if the resulting correlation
functions will inherit the mathematical properties (integrability, generalized
homogeneity, scaling laws) of its parent potentials, and we will also use these
correlation functions to study the behavior of macroscopic systems far from
equilibrium, specially in the neighborhood of critical points or dynamic phase
transitions. As a working example we will consider the mono-critical behavior
of a non-equilibrium binary fluid mixture close to its consolute point.Comment: 23 pages, 3 figures, 1 tabl
A Study of Gaussianity in CMB band maps
The detection of non-Gaussianity in the CMB data would rule out a number of
inflationary models. A null detection of non-Gaussianity, instead, would
exclude alternative models for the early universe. Thus, a detection or
non-detection of primordial non-Gaussianity in the CMB data is crucial to
discriminate among inflationary models, and to test alternative scenarios.
However, there are various non-cosmological sources of non-Gaussianity. This
makes important to employ different indicators in order to detect distinct
forms of non-Gaussianity in CMB data. Recently, we proposed two new indicators
to measure deviation from Gaussianity on large angular scales, and used them to
study the Gaussianity of the raw band WMAP maps with and without the KQ75 mask.
Here we extend this work by using these indicators to perform similar analyses
of deviation from Gaussianity of the foreground-reduced Q, V, and W band maps.
We show that there is a significant deviation from Gaussianity in the
considered full-sky maps, which is reduced to a level consistent with
Gaussianity when the KQ75 mask is employed.Comment: 5 pages, 2 PS figures, uses ws-ijmpd.cls ; to be published in the
International Journal of Modern Physics
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