Static quark anti-quark interactions in zero and finite temperature QCD. I. Heavy quark free energies, running coupling and quarkonium binding

We analyze heavy quark free energies in 2-flavor QCD at finite temperature and the corresponding heavy quark potential at zero temperature. Static quark anti-quark sources in color singlet, octet and color averaged channels are used to probe thermal modifications of the medium. The temperature dependence of the running coupling, $\alpha_{qq}(r,T)$, is analyzed at short and large distances and is compared to zero temperature as well as quenched calculations. In parts we also compare our results to recent findings in 3-flavor QCD. We find that the characteristic length scale below which the running coupling shows almost no temperature dependence is almost twice as large as the Debye screening radius. Our analysis supports recent findings which suggest that $\chi_c$ and $\psi\prime$ are suppressed already at the (pseudo-) critical temperature and thus give a probe for quark gluon plasma production in heavy ion collision experiments, while $J/\psi$ may survive the transition and will dissolve at higher temperatures.Comment: 16 pages, 15 encapsulated postscript figures, revtex

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 $J/\psi$ may survive the phase transition as a bound state, while $\chi_c$ and $\psi'$ 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

Attribution of injury in the shrimp antidumping case: A simultaneous equations approach

We apply a simultaneous equations framework, similar to that of Prusa and Sharp (2001), to the recent shrimp antidumping investigation in order to determine how much injury to the domestic industry—proxied by deterioration in domestic shrimp prices—is attributable to subject imports versus other market factors. We construct an econometric model then estimated with three-stage least squares (3SLS). We then apply the movements of each explanatory variable over the period of investigation (POI) to its respective coefficient in order to determine how much injury is attributable to that particular market factor. We find that subject and non-subject imports were essentially equal causes of injury to the domestic industry.3SLS

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

Heavy quark free energies and the renormalized Polyakov loop in full QCD

We study the renormalized free energy of a heavy quark anti-quark pair in the different colour channels in full QCD at finite temperature. Similarities and differences to the quenched case are discussed and the temperature dependence as well as their short distance behavior are analyzed. 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.Comment: 8 pages, 7 figures, ptptex, Talk at Finite Density QCD at Nara, Japan, 10-12 July 200