46 research outputs found
Quark antiquark energies and the screening mass in a Quark-Gluon plasma at low and high temperatures
We discuss quark antiquark energies and the screening mass in hot QCD using
the non-perturbative lattice approach. For this purpose we analyze properties
of quark antiquark energies and entropies at infinitely large separation of the
quark antiquark pair at low and high temperatures. In the limit of high
temperatures these energies and entropies can be related perturbatively to the
temperature dependence of the Debye mass and the coupling. On the one hand our
analysis thus suggests that the quark antiquark energies at (infinite) large
distances are rather related to the Debye screening mass and the coupling than
to the temperature dependence of heavy-light meson masses. On the other hand we
find no or only little differences in all mass scales introduced by us when
changing from quenched to 2-flavor QCD at temperatures which are only
moderately above the phase transition.Comment: 5 pages, 2 figures, To appear in the proceedings of Workshop on
Extreme QCD, Swansea, Wales, 2-5 Aug 200
Static quark anti-quark free and internal energy in 2-flavor QCD and bound states in the QGP
We present results on heavy quark free energies in 2-flavour QCD. The
temperature dependence of the interaction between static quark anti-quark pairs
will be analyzed in terms of temperature dependent screening radii, which give
a first estimate on the medium modification of (heavy quark) bound states in
the quark gluon plasma. Comparing those radii to the (zero temperature) mean
squared charge radii of cha rmonium states indicates that the may
survive the phase transition as a bound state, while and are
expected to show significant thermal modifications at temperatures close to the
transition. Furthermore we will analyze the relation between heavy quark free
energies, entropy contributions and internal energy and discuss their relation
to potential models used to analyze the melting of heavy quark bound states
above the deconfinement temperature. Results of different groups and various
potential models for bound states in the deconfined phase of QCD are compared.Comment: 6 pages, 8 figures, Lattice 2005 (Finite temperature and density
On the renormalization of the Polyakov loop
We discuss a non-perturbative renormalization of n-point Polyakov loop
correlation functions by explicitly introducing a renormalization constant for
the Polyakov loop operator on a lattice deduced from the short distance
properties of 2-point correlators. We calculate this constant for the
SU(3)gauge theory.Comment: 5 pages, 1 figure, To appear in the proceedings of Workshop on Strong
and Electroweak Matter (SEWM 2002), Heidelberg, Germany, 2-5 Oct 200
Heavy quark free energies, potentials and the renormalized Polyakov loop
We discuss the renormalized free energy of a heavy quark anti-quark pair in
the color singlet channel for quenched and full QCD at finite temperature. The
temperature and mass dependence, as well as its short distance behavior is
analyzed. Using the free energies we calculate the heavy quark potential and
entropy in quenched QCD. The asymptotic large distance behavior of the free
energy is used to define the non-perturbatively renormalized Polyakov loop
which is well behaved in the continuum limit. String breaking is studied in the
color singlet channel in 2-flavor QCD.Comment: 3 pages, Lattice2003(nonzero
An new order parameter with renormalized Polyakov loops
It is well established that physical quantities like the heavy quark
potentials get temperature independent at sufficiently short distances. As a
first application of this feature we suggest a new order parameter for the
confinement/deconfinement phase transition. Our investigations are based on
recent lattice studies.Comment: 2 pages, 2 figures, contribution to 'Statistical QCD', Bielefeld,
August 26-30, 200
Renormalized quark-anti-quark free energy
We present results on the renormalized quark-anti-quark free energy in SU(3)
gauge theory at finite temperatures. We discuss results for the singlet, octet
and colour averaged free energies and comment on thermal relations which allow
to extract separately the potential energy and entropy from the free energy.Comment: 5 pages, 2 figures, To appear in the proceedings of Workshop on
Strong and Electroweak Matter (SEWM 2002), Heidelberg, Germany, 2-5 Oct 200
Static quark anti-quark free energy and the running coupling at finite temperature
We analyze the free energy of a static quark anti-quark pair in quenched QCD
at short and large distances. From this we deduce running couplings, g^2(r,T),
and determine the length scale that separates at high temperature the short
distance perturbative regime from the large distance non-perturbative regime in
the QCD plasma phase. Ambiguities in the definition of a coupling beyond the
perturbative regime are discussed in their relation to phenomenological
considerations on heavy quark bound states in the quark gluon plasma. Our
analysis suggests that it is more appropriate to characterize the
non-perturbative properties of the QCD plasma phase close to T_c in terms
remnants of the confinement part of the QCD force rather than a strong
Coulombic force.Comment: 8 pages, 9 EPS-files, revtex
Lattice calculation of medium effects at short and long distances
We investigate medium effects in QCD like chromoelectric screening and
quasi-particle mass generation by calculating the heavy quark potential as well
as the temporal quark and gluon Coulomb gauge propagators in quenched
approximation.Comment: To appear in proceedings of Quark Matter 2001, 4 pages LaTeX, uses
espcrc1.st
Short distance physics with heavy quark potentials
We present lattice studies of heavy quark potentials in the quenched
approximation of QCD at finite temperatures. Both, the color singlet and color
averaged potentials are calculated. While the potentials are well known at
large distances, we give a detailed analysis of their short distance behavior
(from 0.015 fm to 1 fm) near the critical temperature. At these distances we
expect that the T-dependent potentials go over into the zero temperature
potential. Indeed, we find evidences that the temperature influence gets
suppressed and the potentials starts to become a unique function of the
underlying distance scale. We use this feature to normalize the heavy quark
potentials at short distances and extract the free energy of the quark system
in a gluonic heat bath.Comment: Lattice2001(hightemp), 3 pages, 2 figure
Heavy Quarkonia and Quark Drip Lines in Quark-Gluon Plasma
Using the potential model and thermodynamical quantities obtained in lattice
gauge calculations, we determine the spontaneous dissociation temperatures of
color-singlet quarkonia and the `quark drip lines' which separate the region of
bound states from the unbound region. The dissociation temperatures
of and in quenched QCD are found to be 1.62 and
respectively, in good agreement with spectral function analyses. The
dissociation temperature of in full QCD with 2 flavors is found to be
1.42. For possible bound quarkonium states with light quarks, the
characteristics of the quark drip lines severely limit the stable region close
to the phase transition temperature. Bound color-singlet quarkonia with light
quarks may exist very near the phase transition temperature if their effective
quark mass is of the order of 300-400 MeV and higher.Comment: 8 pages, 2 figures, in LaTex, invited talk presented at the
International Conference on Strangeness in Quark Matter, UCLA, March 26-31,
200