1,291 research outputs found
Off-diagonal Gluon Mass Generation and Infrared Abelian Dominance in Maximally Abelian Gauge in SU(3) Lattice QCD
In SU(3) lattice QCD formalism, we propose a method to extract gauge fields
from link-variables analytically. With this method, we perform the first study
on effective mass generation of off-diagonal gluons and infrared Abelian
dominance in the maximally Abelian (MA) gauge in the SU(3) case. Using SU(3)
lattice QCD, we investigate the propagator and the effective mass of the gluon
fields in the MA gauge with U(1)_3 \timesU(1)_8 Landau gauge fixing. The
Monte Carlo simulation is performed on at =5.7, 5.8 and 6.0 at
the quenched level. The off-diagonal gluons behave as massive vector bosons
with the approximate effective mass in the region of fm, and the propagation is
limited within a short range, while the propagation of diagonal gluons remains
even in a large range. In this way, infrared Abelian dominance is shown in
terms of short-range propagation of off-diagonal gluons. Furthermore, we
investigate the functional form of the off-diagonal gluon propagator. The
functional form is well described by the four-dimensional Euclidean Yukawa-type
function with
for fm. This also indicates that the spectral function of
off-diagonal gluons has the negative-value region
Does the three site Higgsless model survive the electroweak precision tests at loop?
We complete the list of one loop renormalization group equations and matching
conditions relevant for the computation of the electroweak precision parameters
and in the three site Higgsless model. We obtain one-loop formulas for
and expressed in terms of physical observables such as the KK gauge
boson mass , the KK fermion mass , and the KK gauge boson ()
couplings with light quarks and leptons . It is shown that these
physical observables, , and are severely constrained by
the electroweak precision data. Unlike the tree level analysis on the ideally
delocalized fermion, we find that perfect fermiophobity of is ruled out by
the precision data. We also study the cutoff dependence of our analysis.
Although the model is non-renormalizable, the dependence on the cutoff
parameter is shown to be non-significant.Comment: 13pages, 5figures, minor corrections made, references adde
Enrichment of the r-process Element Europium in the Galactic Halo
We investigate the enrichment of europium, as a representative of r-process
elements, in the Galactic halo. In present chemical evolution models, stars are
assumed to be formed through shock processes by supernovae (SNe). The
enrichment of the interstellar medium is calculated by a one-zone approach. The
observed large dispersions in [Eu/Fe] for halo stars, converging with
increasing metallicity, can be explained with our models. In addition, the mass
range of SNe for the {\it r}-process site is constrained to be either stars of
or .Comment: 5 pages (including 4 figures), LaTeX, uses aas2pp4.sty, accepted to
ApJ
Enhancement of W+/- H-/+ Production at Hadron Colliders in the Two Higgs Doublet Model
We discuss the associated W+/- H-/+ production at the CERN Large Hadron
Collider. The dependence of the hadronic cross section on the Higgs sector
parameters is investigated in detail in the framework of the general Two Higgs
Doublet Model (THDM). We study the possible enhancement of the THDM prediction
for the cross section compared to the prediction of the Minimal Supersymmetric
Standard Model (MSSM). We find regions in the THDM parameter space where the
THDM prediction can exceed the one of the MSSM by two orders of magnitude.
These regions of large cross section are in agreement with theoretical bounds
on the model, derived from the requirement of vacuum stability and perturbative
unitarity, and are not excluded by experimental constraints.Comment: 19 pages, 5 figure
NMR Line Shape Analysis of a Multi-state Ligand Binding Mechanism in Chitosanase
Chitosan interaction with chitosanase was examined through analysis of spectral line shapes in the NMR HSQC titration experiments. We established that the substrate, chitosan hexamer, binds to the enzyme through the three-state induced-fit mechanism with fast formation of the encounter complex followed by slow isomerization of the bound-state into the final conformation. Mapping of the chemical shift perturbations in two sequential steps of the mechanism highlighted involvement of the substrate-binding subsites and the hinge region in the binding reaction. Equilibrium parameters of the three-state model agreed with the overall thermodynamic dissociation constant determined by ITC. This study presented the first kinetic evidence of the induced-fit mechanism in the glycoside hydrolases
Z to b bbar and Chiral Currents in Higgsless Models
In this note we compute the flavor-dependent chiral-logarithmic corrections
to the decay Z to b bbar in the three site Higgsless model. We compute these
corrections diagrammatically in the "gaugeless" limit in which the electroweak
couplings vanish. We also compute the chiral-logarithmic corrections to the
decay Z to b bbar using an RGE analysis in effective field theory, and show
that the results agree. In the process of this computation, we compute the form
of the chiral current in the gaugeless limit of the three-site model, and
consider the generalization to the N-site case. We elucidate the Ward-Takahashi
identities which underlie the gaugeless limit calculation in the three-site
model, and describe how the result for the Z to b bbar amplitude is obtained in
unitary gauge in the full theory. We find that the phenomenological constraints
on the three-site Higgsless model arising from measurements of Z to b bbar are
relatively mild, requiring only that the heavy Dirac fermion be heavier than 1
TeV or so, and are satisfied automatically in the range of parameters allowed
by other precision electroweak data.Comment: 19 pages, 7 embedded eps figures (additional reference added
One-Loop Corrections to the S and T Parameters in a Three Site Higgsless Model
In this paper we compute the the one-loop chiral logarithmic corrections to
the S and T parameters in a highly deconstructed Higgsless model with only
three sites. In addition to the electroweak gauge bosons, this model contains a
single extra triplet of vector states (which we denote \rho^{\pm} and \rho^0),
rather than an infinite tower of "KK" modes. We compute the corrections to S
and T in 'tHooft-Feynman gauge, including the ghost, unphysical
Goldstone-boson, and appropriate "pinch" contributions required to obtain
gauge-invariant results for the one-loop self-energy functions. We demonstrate
that the chiral-logarithmic corrections naturally separate into two parts, a
model-independent part arising from scaling below the \rho mass, which has the
same form as the large Higgs-mass dependence of the S or T parameter in the
standard model, and a second model-dependent contribution arising from scaling
between the \rho mass and the cutoff of the model. The form of the universal
part of the one-loop result allows us to correctly interpret the
phenomenologically derived limits on the S and T parameters (which depend on a
"reference" Higgs-boson mass) in this three-site Higgsless model. Higgsless
models may be viewed as dual to models of dynamical symmetry breaking akin to
"walking technicolor", and in these terms our calculation is the first to
compute the subleading 1/N corrections to the S and T parameters. We also
discuss the reduction of the model to the ``two-site'' model, which is the
usual electroweak chiral lagrangian, noting the ``non-decoupling''
contributions present in the limit as M_\rho goes to infinity.Comment: 58 pages; uses JHEP and axodraw. Extensively corrected to incorporate
consistent perturbative expansion, additional pinch contributions, and
running of delocalization parameter. Footnotes adde
AIR TEMPERATURE AND SUNLIGHT INTENSITY OF DIFFERENT GROWING PERIOD AFFECTS THE BIOMASS, LEAF COLOR AND BETACYANIN PIGMENT ACCUMULATIONS IN RED AMARANTH (AMARANTHUS TRICOLOR L.)
The objectives of this study were to determine the effects of daily air temperature and sunlight intensity variations on biomass production, leaf color and betacyanin accumulations in red amaranth (Amaranthus tricolor L.). For this purpose, two improved cultivars; BARI-1 and Altopati were grown in seven different period (from April to October, 2006) under vinyl house condition in the experimental facilities of Gifu University, Japan. The mean daily temperatures
fluctuated from 18 (growing month- April) to 29ÂșC (August), while the mean sunlight intensities varied from 850 (October) to 1257 ÎŒmol m-2 S-1 (August). The highest biomass yield and betacyanin accumulation was obtained in the warmer growing period (July and August) at 28 to 29ÂșC mean air temperatures and 1240 to 1257 ÎŒmol m-2 S-1 sunlight intensity. At the warmer growing period red amaranth produced red leaves with high color index, which
enhanced the betacyanin accumulations. The biomass yield and betacyanin accumulations were reduced significantly in the growing period/month April and October under low temperature regimes (mean air temperature 18 and 19ÂșC, respectively). However, growing periodâs air temperature contributed more for biomass and betacyanin accumulations in red amaranth than sunlight intensity. Comparing two cultivars the biomass yield of BARI-1 was higher biomass yield than that of Altopati and Altopati highlighted with the higher betacyanin accumulations than that of BARI-1 in all growing period. Quantification of the effects of daily air temperature and sunlight intensity on biomass and betacyanin accumulation is important for growers producing these crops for fresh market and also optimize the best growing period. Therefore the influence of air temperatures and sunlight intensity should be considered while grown
red amaranth for maximum yield with bioactive compounds like betacyanin and should be grown in between 28 to 29ÂșC air temperature and 1240 to 1257 ÎŒmol.m-2.S-1. of sunlight intensity
Kaluza-Klein Multi-Black Holes in Five-Dimensional Einstein-Maxwell Theory
We construct the Kaluza-Klein multi-black hole solutions on the
Gibbons-Hawking multi-instanton space in the five-dimensional Einstein-Maxwell
theory. We study geometric properties of the multi-black hole solutions. In
particular, unlike the Gibbons-Hawking multi-instanton solutions, each
nut-charge is able to take a different value due to the existence of black hole
on it. The spatial cross section of each horizon can be admitted to have the
topology of a different lens space L(n;1)=S^3/Z_n addition to S^3.Comment: 8 pages, to be published in Classical and Quantum Gravit
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