142,898 research outputs found
Towards a CPT Invariant Quantum Field Theory on Elliptic de Sitter Space
Consequences of Schr\"{o}dinger's antipodal identification on quantum field
theory in de Sitter space are investigated. The elliptic
identification provides observers with complete information. We show that a
suitable confinement on dimension of the elliptic de Sitter space guarantees
the existence of globally defined spinors and orientable
manifold. In Beltrami coordinates, we give exact solutions of scalar and spinor
fields. The CPT invariance of quantum field theory on the elliptic de Sitter
space is presented explicitly.Comment: 16 pages, some references have been added, the structure of paper
have been revised, accepted for publication in Int. J. Mod. Phys.
A Two-Tiered Correlation of Dark Matter with Missing Transverse Energy: Reconstructing the Lightest Supersymmetric Particle Mass at the LHC
We suggest that non-trivial correlations between the dark matter particle
mass and collider based probes of missing transverse energy H_T^miss may
facilitate a two tiered approach to the initial discovery of supersymmetry and
the subsequent reconstruction of the LSP mass at the LHC. These correlations
are demonstrated via extensive Monte Carlo simulation of seventeen benchmark
models, each sampled at five distinct LHC center-of-mass beam energies,
spanning the parameter space of No-Scale F-SU(5).This construction is defined
in turn by the union of the Flipped SU(5) Grand Unified Theory, two pairs of
hypothetical TeV scale vector-like supersymmetric multiplets with origins in
F-theory, and the dynamically established boundary conditions of No-Scale
Supergravity. In addition, we consider a control sample comprised of a standard
minimal Supergravity benchmark point. Led by a striking similarity between the
H_T^miss distribution and the familiar power spectrum of a black body radiator
at various temperatures, we implement a broad empirical fit of our simulation
against a Poisson distribution ansatz. We advance the resulting fit as a
theoretical blueprint for deducing the mass of the LSP, utilizing only the
missing transverse energy in a statistical sampling of >= 9 jet events.
Cumulative uncertainties central to the method subsist at a satisfactory 12-15%
level. The fact that supersymmetric particle spectrum of No-Scale F-SU(5) has
thrived the withering onslaught of early LHC data that is steadily decimating
the Constrained Minimal Supersymmetric Standard Model and minimal Supergravity
parameter spaces is a prime motivation for augmenting more conventional LSP
search methodologies with the presently proposed alternative.Comment: JHEP version, 17 pages, 9 Figures, 2 Table
Entropy and Long range correlations in literary English
Recently long range correlations were detected in nucleotide sequences and in
human writings by several authors. We undertake here a systematic investigation
of two books, Moby Dick by H. Melville and Grimm's tales, with respect to the
existence of long range correlations. The analysis is based on the calculation
of entropy like quantities as the mutual information for pairs of letters and
the entropy, the mean uncertainty, per letter. We further estimate the number
of different subwords of a given length . Filtering out the contributions
due to the effects of the finite length of the texts, we find correlations
ranging to a few hundred letters. Scaling laws for the mutual information
(decay with a power law), for the entropy per letter (decay with the inverse
square root of ) and for the word numbers (stretched exponential growth with
and with a power law of the text length) were found.Comment: 8 page
Heat conduction and Wiedemann-Franz Law in disordered Luttinger Liquids
We consider heat transport in a Luttinger liquid (LL) with weak disorder and
study the Lorenz number for this system. We start at a high- regime, and
calculate both the electrical and thermal conductivities using a memory
function approach. The resulting Lorenz number is independent of but
depends explicitly on the LL exponents. Lowering , however, allows for a
renormalization of the LL exponents from their bare values by disorder, causing
a violation of the Wiedemann-Franz law. Finally, we extend the discussion to
quantum wire systems and study the wire size dependence of the Lorenz number.Comment: 4 pages, 1 eps figure; Changes made to address Referees' comment
Birational cobordism invariance of uniruled symplectic manifolds
A symplectic manifold is called {\em (symplectically) uniruled}
if there is a nonzero genus zero GW invariant involving a point constraint. We
prove that symplectic uniruledness is invariant under symplectic blow-up and
blow-down. This theorem follows from a general Relative/Absolute correspondence
for a symplectic manifold together with a symplectic submanifold. A direct
consequence is that symplectic uniruledness is a symplectic birational
invariant. Here we use Guillemin and Sternberg's notion of cobordism as the
symplectic analogue of the birational equivalence.Comment: To appear in Invent. Mat
RBSC-NVSS Sample. I. Radio and Optical Identifications of a Complete Sample of 1500 Bright X-ray Sources
We cross-identified the ROSAT Bright Source Catalog (RBSC) and the NRAO VLA
Sky Survey (NVSS) to construct the RBSC-NVSS sample of the brightest X-ray
sources (>= 0.1 counts/s or ~1E-12 ergs/cm/cm/s in the 0.1-2.4 keV band) that
are also radio sources (S >= 2.5 mJy at 1.4 GHz) in the 7.8 sr of extragalactic
sky with |b| > 15 degrees. and delta > -40 degrees. The sky density of NVSS
sources is low enough that they can be reliably identified with RBSC sources
having average rms positional uncertainties = 10 arcsec. We used the more
accurate radio positions to make reliable X-ray/radio/optical identifications
down to the POSS plate limits. We obtained optical spectra for many of the
bright identifications lacking published redshifts. The resulting X-ray/radio
sample is unique in its size (N ~ 1500 objects), composition (a mixture of
nearly normal galaxies, Seyfert galaxies, quasars, and clusters), and low
average redshift ( ~ 0.1).Comment: 35 LaTeX pages including 6 eps figures + 40 LaTeX page table2
(landscape) w/ AASTeX 5.0; accepted to ApJ
Latest results from the PHOBOS experiment
Over the past years PHOBOS has continued to analyze the large datasets
obtained from the first five runs of the Relativistic Heavy Ion Collider (RHIC)
at Brookhaven National Laboratory. The two main analysis streams have been
pursued. The first one aims to obtain a broad and systematic survey of global
properties of particle production in heavy ion collisions. The second class
includes the study of fluctuations and correlations in particle production.
Both type of studies have been performed for a variety of the collision
systems, covering a wide range in collision energy and centrality. The uniquely
large angular coverage of the PHOBOS detector and its ability to measure
charged particles down to very low transverse momentum is exploited. The latest
physics results from PHOBOS, as presented at Quark Matter 2008 Conference, are
contained in this report.Comment: 9 pages, 9 figures, presented at the 20th International Conference on
Ultra-Relativistic Nucleus-Nucleus Collisions, "Quark Matter 2008", Jaipur,
India, Feb.4-10, 200
Existence and equilibration of global weak solutions to Hookean-type bead-spring chain models for dilute polymers
We show the existence of global-in-time weak solutions to a general class of
coupled Hookean-type bead-spring chain models that arise from the kinetic
theory of dilute solutions of polymeric liquids with noninteracting polymer
chains. The class of models involves the unsteady incompressible Navier-Stokes
equations in a bounded domain in two or three space dimensions for the velocity
and the pressure of the fluid, with an elastic extra-stress tensor appearing on
the right-hand side in the momentum equation. The extra-stress tensor stems
from the random movement of the polymer chains and is defined by the Kramers
expression through the associated probability density function that satisfies a
Fokker-Planck-type parabolic equation, a crucial feature of which is the
presence of a center-of-mass diffusion term. We require no structural
assumptions on the drag term in the Fokker-Planck equation; in particular, the
drag term need not be corotational. With a square-integrable and
divergence-free initial velocity datum for the Navier-Stokes equation and a
nonnegative initial probability density function for the Fokker-Planck
equation, which has finite relative entropy with respect to the Maxwellian of
the model, we prove the existence of a global-in-time weak solution to the
coupled Navier-Stokes-Fokker-Planck system. It is also shown that in the
absence of a body force, the weak solution decays exponentially in time to the
equilibrium solution, at a rate that is independent of the choice of the
initial datum and of the centre-of-mass diffusion coefficient.Comment: 86 page
- …