Dissipation at Two-Loop Level: Undressing the Chiral Condensate

A simple and consistent real time analysis of the long-wavelength chiral condensate fields in the background of hard thermal modes is presented in the framework of the linear sigma model. Effective evolution equations are derived for the inhomogeneous condensate fields coupled to a heat bath. Multiple effects of the thermal background on the disoriented chiral condensate are studied using linear response theory. We determine the temperature dependence of the equilibrium condensate, and examine the modification of the sigma and pion dispersion relations as these mesons traverse a hot medium. We calculate the widths by determining the dissipative coefficients at nonzero temperature at one- and two-loop order with resummed meson masses. Our results show that not only decay processes, but elastic scattering processes are significant at high temperatures, yielding to short relaxation times in the phase transition region. The relaxation times obtained are shorter than in previous estimates, making the observation of DCC signals questionable. Throughout this work Goldstone's Theorem is fulfilled when chiral symmetry is spontaneously broken.Comment: 32 pages, 9 ps figure

On the Temperature-Dependence of Quarkonia Correlators

Here I review the temperature-dependence of heavy quarkonia correlators in potential models with three different screened potentials, and compare these to the results from lattice QCD. None of the potentials investigated yield results consistent with the lattice data, indicating that screening is likely not the mechanism for heavy quarkonia suppression. I also discuss a simple toy model, not based on temperature-dependent screening, that can reproduce the lattice results.Comment: based on the talk presented at the 22nd Winter Workshop on Nuclear Dynamics, La Jolla, California, 11-19 March, 200

Quarkonium correlators at finite temperature and potential models

We discuss the calculations of quarkonium spectral functions in potential models and their implications for the interpretation of the lattice data on quarkonium correlators. In particular, we find that melting of different quarkonium states does not lead to significant change in the Euclidean time correlators. The large change of the quarkonium correlators above deconfinement observed in the scalar and axial-vector channels appears to be due to the zero mode contribution.Comment: 8 pages LaTeX, contribution to Lattice 2007, July 30-4 August 2007, Regensburg, German

Describing Charmonium Correlation Functions in Euclidean Time

We present a detailed investigation of the quark mass-dependence of charmonium correlators in Euclidean-time obtained using a potential model, as well as the comparison with results on isotropic lattice calculations performed at several lattice spacings.Comment: Talk given at Zimanyi 75 Memorial Workshop on Hadronic and Quark Matter, Budapest, Hungary, 2-4 Jul 2007. To appear in EJ

Color Screening Melts Quarkonium

We calculate quarkonium spectral functions in a quark-gluon plasma using a potential model based on full QCD lattice calculations of the free energy of static quark-antiquark pair. We estimate the binding energy and the thermal width of different quarkonium states. The estimated upper limit for the dissociation temperatures is considerably lower than the ones suggested in the recent literature.Comment: 4 pages. version to be published in Phys. Rev. Let

Predictions for Quarkonia Dissociation

We predict the upper bound on the dissociation temperatures of different quarkonium states.Comment: 2 pages, 2 figures, Presented at Heavy Ion Collisions at the LHC: Last Call for Prediction

Gluon Propagator and Heavy Quark Potential in an Anisotropic QCD Plasma

The hard-loop resummed propagator in an anisotropic QCD plasma in general linear gauges are computed. We get the explicit expressions of the gluon propagator in covariant gauge, Coulomb gauge and temporal axial gauge. Considering one gluon exchange, the potential between heavy quarks is defined through the Fourier transform of the static propagator. We find that the potential exhibits angular dependence and that there is stronger attraction on distance scales on the order of the inverse Debye mass for quark pairs aligned along the direction of anisotropy than for transverse alignment.Comment: 4 pages, to be published in the proceedings of SEWM 2008, Nucl. Phys. A, in prin