1,283 research outputs found
On the Wilson loop in the dual representation within the dual Higgs model with dual Dirac strings
The vacuum expectation value of the Wilson loop in the dual representation is
calculated in the dual Higgs model with dual Dirac strings. It is shown that
the averaged value of the Wilson loop in the dual representation obeys the
area-law falloff. Quantum fluctuations of the dual-vector and the Higgs field
around Abrikosov flux lines induced by dual Dirac strings in a dual
superconducting vacuum and string shape fluctuations are taken into account.Comment: 9 pages, latex, no figure
QCD sum rules with finite masses
The concept of QCD sum rules is extended to bound states composed of
particles with finite mass such as scalar quarks or strange quarks. It turns
out that mass corrections become important in this context. The number of
relevant corrections is analyzed in a systematic discussion of the IR- and
UV-divergencies, leading in general to a finite number of corrections. The
results are demonstrated for a system of two massless quarks and two heavy
scalar quarks.Comment: 15 pages, including two pictures to be found in an extra file. Latex
neads epsf.st
Quantum interference in nanofractals and its optical manifestation
We consider quantum interferences of ballistic electrons propagating inside
fractal structures with nanometric size of their arms. We use a scaling
argument to calculate the density of states of free electrons confined in a
simple model fractal. We show how the fractal dimension governs the density of
states and optical properties of fractal structures in the RF-IR region. We
discuss the effect of disorder on the density of states along with the
possibility of experimental observation.Comment: 19 pages, 6 figure
Generalized Drinfeld-Sokolov Hierarchies II: The Hamiltonian Structures
In this paper we examine the bi-Hamiltonian structure of the generalized
KdV-hierarchies. We verify that both Hamiltonian structures take the form of
Kirillov brackets on the Kac-Moody algebra, and that they define a coordinated
system. Classical extended conformal algebras are obtained from the second
Poisson bracket. In particular, we construct the algebras, first
discussed for the case and by A. Polyakov and M. Bershadsky.Comment: 41 page
Dynamics near the critical point: the hot renormalization group in quantum field theory
The perturbative approach to the description of long wavelength excitations
at high temperature breaks down near the critical point of a second order phase
transition. We study the \emph{dynamics} of these excitations in a relativistic
scalar field theory at and near the critical point via a renormalization group
approach at high temperature and an expansion in
space-time dimensions. The long wavelength physics is determined by a
non-trivial fixed point of the renormalization group. At the critical point we
find that the dispersion relation and width of quasiparticles of momentum
is and respectively, the
group velocity of quasiparticles vanishes in the long
wavelength limit at the critical point. Away from the critical point for
we find and
with
the finite temperature correlation length . The
new \emph{dynamical} exponent results from anisotropic renormalization in
the spatial and time directions. For a theory with O(N) symmetry we find . Critical slowing down,
i.e, a vanishing width in the long-wavelength limit, and the validity of the
quasiparticle picture emerge naturally from this analysis.Comment: Discussion on new dynamical universality class. To appear in Phys.
Rev.
Bacterial dimethylsulfoniopropionate degradation genes in the oligotrophic North Pacific subtropical gyre
Dimethylsulfoniopropionate (DMSP) is an organic sulfur compound that is rapidly metabolized by marine bacteria either by cleavage to dimethylsulfide (DMS) or demethylation to 3-methiolpropionate. The abundance and diversity of genes encoding bacterial DMS production (dddP) and demethylation (dmdA) were measured in the North Pacific subtropical gyre (NPSG) between May 2008 and February 2009 at Station ALOHA (22°45=N, 158°00=W) at two depths: 25mand the deep chlorophyll maximum (DCM;~100 m). The highest abundance of dmdA genes was in May 2008 at 25 m, with~16.5% of cells harboring a gene in one of the eight subclades surveyed, while the highest abundance of dddP genes was in July 2008 at 25 m, with~2% of cells harboring a gene. The dmdA gene pool was consistently dominated by homologs from SAR11 subclades, which was supported by findings in metagenomic data sets derived from Station ALOHA. Expression of the SAR11 dmdA genes was low, with typical transcript:gene ratios between 1:350 and 1:1,400. The abundance of DMSP genes was statistically different between 25mand the DCM and correlated with a number of environmental variables, including primary production, photosynthetically active radiation, particulate DMSP, and DMS concentrations. At 25 m, dddP abundance was positively correlated with pigments that are diagnostic of diatoms; at the DCM, dmdA abundance was positively correlated with temperature. Based on gene abundance, we hypothesize that SAR11 bacterioplankton dominate DMSP cycling in the oligotrophic NPSG, with lesser but consistent involvement of other members of the bacterioplankton community
Experimental Evidence of Giant Electron - Gamma Bursts Generated by Extensive Atmospheric Showers in Thunderclouds
The existence of a new phenomena - giant electron-gamma bursts is
established. The bursts are generated in thunderclouds as a result of the
combined action of runaway breakdown and extensive atmosphere showers (RB-EAS).
The experiments were fulfilled at the Tien Shan Mountain Scientific Station
using EAS-Radio installation. This specially constructed installation consists
of a wide spread EAS trigger array and a high time resolution
radiointerferometer.Comment: 30 pages, 16 figure
Density functional study of Au (n=2-20) clusters: lowest-energy structures and electronic properties
We have investigated the lowest-energy structures and electronic properties
of the Au(n=2-20) clusters based on density functional theory (DFT) with
local density approximation. The small Au clusters adopt planar structures
up to n=6. Tabular cage structures are preferred in the range of n=10-14 and a
structural transition from tabular cage-like structure to compact
near-spherical structure is found around n=15. The most stable configurations
obtained for Au and Au clusters are amorphous instead of
icosahedral or fcc-like, while the electronic density of states sensitively
depend on the cluster geometry. Dramatic odd-even alternative behaviors are
obtained in the relative stability, HOMO-LUMO gaps and ionization potentials of
gold clusters. The size evolution of electronic properties is discussed and the
theoretical ionization potentials of Au clusters compare well with
experiments.Comment: 6 pages, 7 figure
Canonical Formulation of the Light-Front Gluodynamics and Quantization of the Non-Abelian Plane Waves
Without a gauge fixing, canonical variables for the light-front SU(2)
gluodynamics are determined. The Gauss law is written in terms of the canonical
variables. The system is qualified as a generalized dynamical system with first
class constraints. Abeliazation is a specific feature of the formulation (most
of the canonical variables transform nontrivially only under the action of an
Abelian subgroup of the gauge transformations). At finite volume, a discrete
spectrum of the light-front Hamiltonian is obtained in the sector of
vanishing . We obtain, therefore, a quantized form of the classical
solutions previously known as non-Abelian plane waves. Then, considering the
infinite volume limit, we find that the presence of the mass gap depends on the
way the infinite volume limit is taken, which may suggest the presence of
different ``phases'' of the infinite volume theory. We also check that the
formulation obtained is in accord with the standard perturbation theory if the
latter is taken in the covariant gauges.Comment: REVTEX, 18 pages, version to appear in Phys. Rev.
Explicitly Covariant Light-Front Dynamics and Relativistic Few-Body Systems
The wave function of a composite system is defined in relativity on a
space-time surface. In the explicitly covariant light-front dynamics, reviewed
in the present article, the wave functions are defined on the plane \omega \cd
x=0, where is an arbitrary four-vector with . The
standard non-covariant approach is recovered as a particular case for . Using the light-front plane is of crucial importance, while the
explicit covariance gives strong advantages emphasized through all the review.
The properties of the relativistic few-body wave functions are discussed in
detail and are illustrated by examples in a solvable model. The
three-dimensional graph technique for the calculation of amplitudes in the
covariant light-front perturbation theory is presented.
The structure of the electromagnetic amplitudes is studied. We investigate
the ambiguities which arise in any approximate light-front calculations, and
which lead to a non-physical dependence of the electromagnetic amplitude on the
orientation of the light-front plane. The elastic and transition form factors
free from these ambiguities are found for spin 0, 1/2 and 1 systems.
The formalism is applied to the calculation of the relativistic wave
functions of two-nucleon systems (deuteron, scattering state), with particular
attention to the role of their new components in the deuteron elastic and
electrodisintegration form factors and to their connection with meson exchange
currents. Straigthforward applications to the pion and nucleon form factors and
the transition are also made.Comment: latex.tar.gz file, 162 pages, 42 figures, to be published in Physics
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