3,232 research outputs found
Gauge potential singularities and the gluon condensate at finite temperatures
The continuum limit of SU(2) lattice gauge theory is carefully investigated
at zero and at finite temperatures. It is found that the continuum gauge field
has singularities originating from center degrees of freedom being discovered
in Landau gauge. Our numerical results show that the density of these
singularities properly extrapolates to a non-vanishing continuum limit. The
action density of the non-trivial Z_2 links is tentatively identified with the
gluon condensate. We find for temperatures larger than the deconfinement
temperature that the thermal fluctuations of the embedded Z_2 gauge theory
result in an increase of the gluon condensate with increasing temperature.Comment: 3 pages, 2 figures, talk presented by K. Langfeld at the 19th
International Symposium on Lattice Field Theory (LATTICE2001), Berlin,
19.-24.8.2001, to appear in the proceeding
Variational solution of the Yang-Mills Schr\"odinger equation in Coulomb gauge
The Yang-Mills Schr\"odinger equation is solved in Coulomb gauge for the
vacuum by the variational principle using an ansatz for the wave functional,
which is strongly peaked at the Gribov horizon. A coupled set of
Schwinger-Dyson equations for the gluon and ghost propagators in the Yang-Mills
vacuum as well as for the curvature of gauge orbit space is derived and solved
in one-loop approximation. We find an infrared suppressed gluon propagator, an
infrared singular ghost propagator and a almost linearly rising confinement
potential.Comment: 24 pages, revtex, 13 figure
Hamiltonian approach to QCD in Coulomb gauge - a survey of recent results
I report on recent results obtained within the Hamiltonian approach to QCD in
Coulomb gauge. Furthermore this approach is compared to recent lattice data,
which were obtained by an alternative gauge fixing method and which show an
improved agreement with the continuum results. By relating the Gribov
confinement scenario to the center vortex picture of confinement it is shown
that the Coulomb string tension is tied to the spatial string tension. For the
quark sector a vacuum wave functional is used which explicitly contains the
coupling of the quarks to the transverse gluons and which results in
variational equations which are free of ultraviolet divergences. The
variational approach is extended to finite temperatures by compactifying a
spatial dimension. The effective potential of the Polyakov loop is evaluated
from the zero-temperature variational solution. For pure Yang--Mills theory,
the deconfinement phase transition is found to be second order for SU(2) and
first order for SU(3), in agreement with the lattice results. The corresponding
critical temperatures are found to be and , respectively. When quarks are included, the deconfinement
transition turns into a cross-over. From the dual and chiral quark condensate
one finds pseudo-critical temperatures of and , respectively, for the deconfinement and chiral transition.Comment: Talk given by H. Reinhardt at "5th Winter Workshop on
Non-Perturbative Quantum Field Theory", 22-24 March 2017, Sophia-Antipolis,
France. arXiv admin note: text overlap with arXiv:1609.09370,
arXiv:1510.03286, arXiv:1607.0814
Energy evolution in time-dependent harmonic oscillator
The theory of adiabatic invariants has a long history, and very important
implications and applications in many different branches of physics,
classically and quantally, but is rarely founded on rigorous results. Here we
treat the general time-dependent one-dimensional harmonic oscillator, whose
Newton equation cannot be solved in general. We
follow the time-evolution of an initial ensemble of phase points with sharply
defined energy at time and calculate rigorously the distribution of
energy after time , which is fully (all moments, including the
variance ) determined by the first moment . For example,
, and all
higher even moments are powers of , whilst the odd ones vanish
identically. This distribution function does not depend on any further details
of the function and is in this sense universal. In ideal
adiabaticity , and the variance is
zero, whilst for finite we calculate , and for the
general case using exact WKB-theory to all orders. We prove that if is of class (all derivatives up to and including the order
are continuous) , whilst for class it is known to be exponential .Comment: 26 pages, 5 figure
Multiconfigurational Hartree-Fock theory for identical bosons in a double well
Multiconfigurational Hartree-Fock theory is presented and implemented in an
investigation of the fragmentation of a Bose-Einstein condensate made of
identical bosonic atoms in a double well potential at zero temperature. The
approach builds in the effects of the condensate mean field and of atomic
correlations by describing generalized many-body states that are composed of
multiple configurations which incorporate atomic interactions. Nonlinear and
linear optimization is utilized in conjunction with the variational and
Hylleraas-Undheim theorems to find the optimal ground and excited states of the
interacting system. The resulting energy spectrum and associated eigenstates
are presented as a function of double well barrier height. Delocalized and
localized single configurational states are found in the extreme limits of the
simple and fragmented condensate ground states, while multiconfigurational
states and macroscopic quantum superposition states are revealed throughout the
full extent of barrier heights. Comparison is made to existing theories that
either neglect mean field or correlation effects and it is found that
contributions from both interactions are essential in order to obtain a robust
microscopic understanding of the condensate's atomic structure throughout the
fragmentation process.Comment: 21 pages, 13 figure
Nonrigid chiral soliton for the octet and decuplet baryons
Systematic treatment of the collective rotation of the nonrigid chiral
soliton is developed in the SU(3) chiral quark soliton model and applied to the
octet and decuplet baryons. The strangeness degrees of freedom are treated by a
simplified bound-state approach which omits the locality of the kaon wave
function. Then, the flavor rotation is divided into the isospin rotation and
the emission and absorption of the kaon. The kaon Hamiltonian is diagonalized
by the Hartree approximation. The soliton changes the shape according to the
strangeness. The baryons appear as the rotational bands of the combined system
of the soliton and the kaon.Comment: 11 pages(LaTex), 1 figures(eps
Representation of a complex Green function on a real basis: I. General Theory
When the Hamiltonian of a system is represented by a finite matrix,
constructed from a discrete basis, the matrix representation of the resolvent
covers only one branch. We show how all branches can be specified by the phase
of a complex unit of time. This permits the Hamiltonian matrix to be
constructed on a real basis; the only duty of the basis is to span the
dynamical region of space, without regard for the particular asymptotic
boundary conditions that pertain to the problem of interest.Comment: about 40 pages with 5 eps-figure
Liver Abscess Severity at Slaughter Does Not Affect Meat Tenderness and Sensory Attributes in Commercially Finished Beef Cattle Fed Without Tylosin Phosphate
Liver abscesses are a significant problem in the United States’ cattle feeding industry, costing the industry an estimated $15.9 million annually in liver condemnation, trim losses, and reduced carcass weights and quality grades. Recent reported incidence rates of liver abscesses at slaughter range from 10 to 20%. Liver abscess incidence may be influenced by a number of factors including: breed, gender, diet, days on feed, cattle type, season, and geographical location. Liver abscesses typically occur secondary to rumen insults caused by acidosis or rumenitis. It has been proposed that pathogens associated with liver abscess formation enter the blood stream through damaged rumen epithelium and are transported to the liver through the portal vein where they cause infection, manifested as liver abscesses. Severe liver abscesses have been linked to reduction in hot carcass weight, dressing percentage, yield grade, longissimus muscle area, and marbling scores of carcasses when compared to those with normal livers. However, the effect of liver abscesses on meat tenderness and sensory attributes has not been previously investigated
NcPred for accurate nuclear protein prediction using n-mer statistics with various classification algorithms
Prediction of nuclear proteins is one of the major challenges in genome annotation. A method, NcPred is described, for predicting nuclear proteins with higher accuracy exploiting n-mer statistics with different classification algorithms namely Alternating Decision (AD) Tree, Best First (BF) Tree, Random Tree and Adaptive (Ada) Boost. On BaCello dataset [1], NcPred improves about 20% accuracy with Random Tree and about 10% sensitivity with Ada Boost for Animal proteins compared to existing techniques. It also increases the accuracy of Fungal protein prediction by 20% and recall by 4% with AD Tree. In case of Human protein, the accuracy is improved by about 25% and sensitivity about 10% with BF Tree. Performance analysis of NcPred clearly demonstrates its suitability over the contemporary in-silico nuclear protein classification research
- …