17 research outputs found
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