2,297 research outputs found
String breaking
We numerically investigate the transition of the static quark-antiquark
string into a static-light meson-antimeson system. Improving noise reduction
techniques, we are able to resolve the signature of string breaking dynamics
for Nf=2 lattice QCD at zero temperature. We discuss the lattice techniques
used and present results on energy levels and mixing angle of the static
two-state system. We visualize the action density distribution in the region of
string breaking as a function of the static colour source-antisource
separation. The results can be related to properties of quarkonium systems.Comment: 8 pages, Talk given at the Workshop on Computational Hadron Physics,
Nicosia, Cyprus, 14--17 September 200
First Evidence of -Dependence in the QCD Interquark Potential
We present a lattice calculation of the interquark potential between static
quarks in a ``full'' QCD simulation with 2 flavours of dynamical Wilson-quarks
at three intermediate sea-quark masses. We work at on lattice
size of with 100 configurations per sea-quark mass. We compare
the full QCD potential with its quenched counterpart at equal lattice spacing,
GeV, which is at the onset of the quenched scaling regime.
We find that the full QCD potential lies consistently below that of quenched
QCD. We see no evidence for string-breaking effects on these lattice volumes,
.Comment: 9 pages (1 tex file epsf-style + 6 ps-figures
Description with a Screened Potential
Recent lattice QCD calculations suggest a rather abrupt transition in the
confinig potential from a linear to a constant behavior. We analyze the effects
of such a fast deconfinement in the simplest non-relativistic system,
bottomonium.Comment: 4 pages. Presented at MENU04, Beijing 2004. To be published by IJMP
The strange quark condensate in the nucleon in 2+1 flavor QCD
We calculate the "strange quark content of the nucleon", ,
which is important for interpreting the results of some dark matter detection
experiments. The method is to evaluate quark-line disconnected correlations on
the MILC lattice ensembles, which include the effects of dynamical strange
quarks. After continuum and chiral extrapolations, the result is <N |s s_bar
|N> = 0.69 +- 0.07(statistical) +- 0.09(systematic), in the modified minimal
subtraction scheme (2 GeV), or for the renormalization scheme invariant form,
m_s partial{M_N}/partial{m_s} = 59(6)(8) MeV.Comment: Added figures and references, especially for fit range choice. Other
changes for clarity. Version to appear in publicatio
The scalar and tensor glueballs in the valence approximation
We evaluate the infinite volume, continuum limit of and
glueball masses in the valence approximation. We find ~MeV and ~MeV, consistent with the interpretation
of as the lightest scalar glueball.Comment: (talk presented by A. Vaccarino at Lattice 93) 3 pages of PostScript
in uufiles compressed form. IBM-HET-94-
Field Strength Formulation of SU(2) Yang-Mills Theory in the Maximal Abelian Gauge: Perturbation Theory
We present a reformulation of SU(2) Yang-Mills theory in the maximal Abelian
gauge, where the non-Abelian gauge field components are exactly integrated out
at the expense of a new Abelian tensor field. The latter can be treated in a
semiclassical approximation and the corresponding saddle point equation is
derived. Besides the non-trivial solutions, which are presumably related to
non-perturbative interactions for the Abelian gauge field, the equation of
motion for the tensor fields allows for a trivial solution as well. We show
that the semiclassical expansion around this trivial solution is equivalent to
the standard perturbation theory. In particular, we calculate the one-loop
-function for the running coupling constant in this approach and
reproduce the standard result.Comment: 29 pages LaTeX, 6 postscript figures. Version to be published in Int.
J. Mod. Phys.
Towards the glueball spectrum of full QCD
We present first results on masses of the scalar and tensor glueballs as well
as of the torelon from simulations of QCD with two light flavours of Wilson
fermions. The gauge configurations of extent 16^3*32 at beta = 5.6 and kappa =
0.156, 0.157 and 0.1575 have been generated as part of the SESAM collaboration
programme. The present lattice resolutions correspond to 1/a = 2.0-2.3 GeV and
ratios m(pi)/m(rho) = 0.83, 0.76 and 0.71, respectively. Studies on larger
lattice volumes and closer to the chiral limit are in progress.Comment: 4 pages, LaTeX, espcrc2 and epsf styles required, 4 epsf figures,
poster presented by G. Bali at Lattice '9
Characterization of typical Tunisian fermented milk, rayeb
Traditional Tunisian fermented milk, rayeb, was produced according to the traditional method. Physicochemical, microstructural, microbiological characteristics and major aromatic compounds evaluation were studied. The results show a decrease in lactose content and pH value and an increase in lactic acid during spontaneous fermentation. The microstructure of rayeb consisted of individualized particles that were coalesced in chains leading to relatively homogeneous sieve. Lactic acid bacteria (LAB) and yeasts present in rayeb were responsible for lactic acid fermentation and aroma development. Dynamic headspace (DHS) extraction procedure shows the existence of four major volatile compounds: acetaldehyde, ethanol, diacetyl and acetoin in the rayeb.Key words: Rayeb, spontaneous fermentation, physicochemical composition, microstructure, microbiological, volatile compounds
Lattice sum rules for the colour fields
We analyse the sum rules describing the action and energy in the colour
fields around glueballs, torelons and static potentials.Comment: 9 pages LATEX, (typos corrected, to appear in Phys Rev D
Deconfinement and Percolation
Using percolation theory, we derive a conceptual definition of deconfinement
in terms of cluster formation. The result is readily applicable to infinite
volume equilibrium matter as well as to finite size pre-equilibrium systems in
nuclear collisions.Comment: 13 pages, latex, six figures include
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