3,754 research outputs found
Spontaneously broken parity and consistent cosmology with transitory domain walls
Domain wall structure which may form in theories with spontaneously broken
parity is generically in conflict with standard cosmology. It has been argued
that Planck scale suppressed effects can be sufficient for removing such domain
walls. We study this possibility for three specific evolution scenarios for the
domain walls, with evolution during radiation dominated era, during matter
dominated era, and that accompanied by weak inflation. We determine the
operators permitted by the supergravity formalism and find that the field
content introduced to achieve desired spontaneous parity breaking makes
possible Planck scale suppressed terms which can potentially remove the domain
walls safely. However, the parity breaking scale, equivalently the majorana
mass scale of the right handed neutrino, does get constrained in some of
the cases, notably for the matter dominated evolution case which would be
generic to string theory inspired models giving rise to moduli fields. One
left-right symmetric model with only triplets and bidoublets is found to be
more constrainted than another admitting a gauge singlet
Implications of Unitarity and Charge Breaking Minima in Left-Right Symmetric Model
We examine the usefulness of the unitarity conditions in Left-Right symmetric
model which can translate into giving a stronger constraint on the model
parameters together with the criteria derived from vacuum stability and
perturbativity. In this light, we demonstrate the bounds on the masses of the
physical scalars present in the model and find the scenario where multiple
scalar modes are in the reach of Large Hadron Collider. We also analyse the
additional conditions that can come from charge breaking minima in this
context.Comment: v2: Accepted for publication in Phys. Rev. D, reference added, minor
change in the text, 16 pages, 2 figure
Improved Universality in the Neutron Star Three-Hair Relations
No-hair like relations between the multipole moments of the exterior
gravitational field of neutron stars have recently been found to be
approximately independent of the star's internal structure. This approximate,
equation-of-state universality arises after one adimensionalizes the multipole
moments appropriately, which then begs the question of whether there are better
ways to adimensionalize the moments to obtain stronger universality. We here
investigate this question in detail by considering slowly-rotating neutron
stars both in the non-relativistic limit and in full General Relativity. We
find that there exist normalizations that lead to stronger equation-of-state
universality in the relations among the moment of inertia and the quadrupole,
octopole and hexadecapole moments of neutron stars. We determine the optimal
normalization that minimizes the equation-of-state dependence in these
relations. The results found here may have applications in the modeling of
X-ray pulses and atomic line profiles from millisecond pulsars with NICER and
LOFT.Comment: 11 pages, 10 figures, submitted to Phys. Rev.
Singularity Free Rainbow Universe
Isotropic quantum cosmological perfect fluid model is studied in the
formalism of Rainbow gravity. It is found that the only surviving matter degree
of freedom played the role of cosmic time. It is possible to find the wave
packet naturally with a suitable choice of the Rainbow functions which resulted
from the superposition of the wave functions of the
Schrdinger-Wheeler-deWitt equation. The many-worlds interpretation of
quantum mechanics is applied to investigate the behavior of the scale factor
and the behaviour is found to depend on the operator ordering. It is shown that
the model in the Rainbow framework naturally avoids singularity and a bouncing
non-singular universe is found.Comment: This essay received an honorable mention in the 2013 Essay
Competition of the Gravity Research Foundatio
Type III Seesaw and Dark Matter in a Supersymmetric Left-Right Model
We propose a new supersymmetric left right model with Higgs doublets carrying
odd B-L charge, higgs bidoublet and heavy Higgs triplets with zero B-L charge
and a set of sterile neutrinos which are singlet under the gauge group. We show
that spontaneous parity violation can be achieved naturally in this model and
the neutrino masses arise from the so called type III seesaw mechanism. We also
discuss the possible phenomenology in the context of neutrino masses and dark
matter
Realization of Semantic Atom Blog
Web blog is used as a collaborative platform to publish and share
information. The information accumulated in the blog intrinsically contains the
knowledge. The knowledge shared by the community of people has intangible value
proposition. The blog is viewed as a multimedia information resource available
on the Internet. In a blog, information in the form of text, image, audio and
video builds up exponentially. The multimedia information contained in an Atom
blog does not have the capability, which is required by the software processes
so that Atom blog content can be accessed, processed and reused over the
Internet. This shortcoming is addressed by exploring OWL knowledge modeling,
semantic annotation and semantic categorization techniques in an Atom blog
sphere. By adopting these techniques, futuristic Atom blogs can be created and
deployed over the Internet
Gravitational Collapse in Gravity's Rainbow
In this paper, we will analyze the gravitational collapse in the framework of
gravity's rainbow. We will demonstrate that the position of the horizon for a
particle inside the black hole depends on the energy of that particle. It will
also be observe that the position of the horizon for a particle falling
radially into the black hole also depends on its energy. Thus, it is possible
for a particle coming from outside to interact with a particle inside the
black, and take some information outside the black hole. This is because for
both these particles the position of horizon is different. So, even though the
particle from inside the black hole is in its own horizon, it is not in the
horizon of the particle coming from outside. Thus, we will demonstrate that in
gravity's rainbow information can get out of a black hole.Comment: accepted in Int. J. Geom. Methods Mod. Phy
Modeling interacting dynamic networks: I. Preferred degree networks and their characteristics
We study a simple model of dynamic networks, characterized by a set preferred
degree, . Each node with degree attempts to maintain its
and will add (cut) a link with probability (). As
a starting point, we consider a homogeneous population, where each node has the
same , and examine several forms of , inspired by
Fermi-Dirac functions. Using Monte Carlo simulations, we find the degree
distribution in steady state. In contrast to the well-known Erd\H{o}s-R\'{e}nyi
network, our degree distribution is not a Poisson distribution; yet its
behavior can be understood by an approximate theory. Next, we introduce a
second preferred degree network and couple it to the first by establishing a
controllable fraction of inter-group links. For this model, we find both
understandable and puzzling features. Generalizing the prediction for the
homogeneous population, we are able to explain the total degree distributions
well, but not the intra- or inter-group degree distributions. When monitoring
the total number of inter-group links, , we find very surprising behavior.
explores almost the full range between its maximum and minimum allowed
values, resulting in a flat steady-state distribution, reminiscent of a simple
random walk confined between two walls. Both simulation results and analytic
approaches will be discussed.Comment: Accepted by JSTA
Higgs vacuum stability and inflationary dynamics after BICEP2 and PLANCK dust polarisation data
If the recent detection of mode polarization of the Cosmic Microwave
Background by BICEP2 observations, withstand the test of time after the release
of recent PLANCK dust polarisation data, then it would surprisingly put the
inflationary scale near Grand Unification scale if one considers single-field
inflationary models. On the other hand, Large Hadron Collider has observed the
elusive Higgs particle whose presently observed mass can lead to electroweak
vacuum instability at high scale GeV). In this
article, we seek for a simple particle physics model which can simultaneously
keep the vacuum of the theory stable and yield high-scale inflation
successfully. To serve our purpose, we extend the Standard Model of particle
physics with a gauged symmetry which spontaneously breaks down
just above the inflationary scale. Such a scenario provides a constrained
parameter space where both the issues of vacuum stability and high-scale
inflation can be successfully accommodated. The threshold effect on the Higgs
quartic coupling due to the presence of the heavy inflaton field plays an
important role in keeping the electroweak vacuum stable. Furthermore, this
scenario is also capable of reheating the universe at the end of inflation.
Though the issues of Dark Matter and Dark Energy, which dominate the late-time
evolution of our universe, cannot be addressed within this framework, this
model successfully describes the early universe dynamics according to the Big
Bang model.Comment: Title and text are modified to match the accepted version in JCAP. 22
pages, 3 figures, Latex fil
Quantum Rainbow Cosmological Model With Perfect Fluid
Isotropic quantum cosmological perfect fluid model is studied in the
formalism of Rainbow gravity. It is found that the only surviving matter degree
of freedom played the role of cosmic time. With the suitable choice of the
Rainbow functions it is possible to find the wave packet naturally from the
superposition of the wave functions of the Schrdinger-Wheeler-deWitt
equation. The many-worlds interpretation of quantum mechanics is applied to
investigate the behavior of the scale factor and the behavior is found to
depend on the operator ordering. It is shown that the model in the Rainbow
framework may avoid singularity yielding a bouncing non-singular universe.Comment: To appear in Int. J. Mod. Phys. D. arXiv admin note: substantial text
overlap with arXiv:1305.370
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