3,019 research outputs found
Charmonia above the Deconfinement Phase Transition
Analyzing correlation functions of charmonia at finite temperature () on
anisotropic lattices by the maximum entropy method (MEM),
we find that and survive as distinct resonances in the plasma
even up to and that they eventually dissociate between and ( is the critical temperature of deconfinement). This
suggests that the deconfined plasma is non-perturbative enough to hold
heavy-quark bound states. The importance of having sufficient number of
temporal data points in the MEM analysis is also emphasized.Comment: Lattice2003(nonzero), 3 pages, 3 figure
Comment on: "Transverse-Mass Dependence of Dilepton Emission from Preequilibrium and Quark-Gluon Plasma in High Energy Nucleus-Nucleus Collisions"
In a recent Letter, Geiger presents calculations of the dilepton emission
from the early stage of ultrarelativistic heavy ion collisions using the parton
cascade model (PCM). He shows that the scaling is not observed. In
this Comment, we point out that this is largely due to a defect in the PCM.Comment: 3 pages, LaTex, LBL-3526
Hadronic Spectral Functions above the QCD Phase Transition
We extract the spectral functions in the scalar, pseudo-scalar, vector, and
axial vector channels above the deconfinement phase transition temperature (Tc)
using the maximum entropy method (MEM). We use anisotropic lattices, 32^3 * 32,
40, 54, 72, 80, and 96 (corresponding to T = 2.3 Tc --> 0.8 Tc), with the
renormalized anisotropy xi = 4.0 to have enough temporal data points to carry
out the MEM analysis. Our result suggests that the spectral functions continue
to possess non-trivial structures even above Tc and in addition that there is a
qualitative change in the state of the deconfined matter between 1.5 Tc and 2
Tc.Comment: 3 pages, 4 figures, Lattice2002(nonzerot
and in the Deconfined Plasma from Lattice QCD
Analyzing correlation functions of charmonia at finite temperature () on
anisotropic lattices by the maximum entropy method (MEM),
we find that and survive as distinct resonances in the plasma
even up to and that they eventually dissociate between and ( is the critical temperature of deconfinement). This
suggests that the deconfined plasma is non-perturbative enough to hold
heavy-quark bound states. The importance of having sufficient number of
temporal data points in MEM analyses is also emphasized.Comment: 4 pages, 4 figures, REVTEX, version to appear in Physical Review
Letter
Non-Central Heavy-Ion Collisions are the Place to Look for DCC
We give two reasons why we believe that non-central ultrarelativistic heavy
ion collisions are the place to look for the disoriented chiral condensates
(DCC). First, we argue that the most probable quench scenario for the formation
of DCC requires non-central collisions. Second, we show by numerical
simulations that strong electromagnetic fields of heavy ions can exert a
surprisingly large effect on the DCC domain formation through the chiral
anomaly. The effect again requires non-central collisions. Interestingly, the
result of simulations is consistent with the formation of correlated two
domains of the chiral condensate, which are aligned in space, perpendicular to
the scattering plane, but misaligned in isospin space.Comment: 4 pages (Latex), 3 embedded ps figures, espcrc1 style, talk given at
Quark Matter 97, December 97, Tsukuba, Japa
Back-to-Back Correlations for Bosons Modified by Medium
Novel back-to-back correlations are shown to arise for thermal ensembles of
squeezed bosonic states associated with medium-modified mass-shifts. The
strength of these correlations could become unexpectedly large in heavy ion
collisions.Comment: Talk given at Quark Matter 99, Torino, Italy, May 10-15, 1999. LaTeX,
4 pages, 2 eps figures. To appear in Nucl. Phys.
Secondary phi meson peak as an indicator of QCD phase transition in ultrarelativistic heavy ion collisions
In a previous paper, we have shown that a double phi peak structure appears
in the dilepton invariant mass spectrum if a first order QCD phase transition
occurs in ultrarelativistic heavy ion collisions. Furthermore, the transition
temperature can be determined from the transverse momentum distribution of the
low mass phi peak. In this work, we extend the study to the case that a smooth
crossover occurs in the quark-gluon plasma to the hadronic matter transition.
We find that the double phi peak structure still exists in the dilepton
spectrum and thus remains a viable signal for the formation of the quark-gluon
plasma in ultrarelativistic heavy ion collisions.Comment: 8 pages, 9 uuencoded postscript figures included, Latex, LBL-3572
Lee-Yang zero analysis for the study of QCD phase structure
We comment on the Lee-Yang zero analysis for the study of the phase structure
of QCD at high temperature and baryon number density by Monte-Carlo
simulations. We find that the sign problem for non-zero density QCD induces a
serious problem in the finite volume scaling analysis of the Lee-Yang zeros for
the investigation of the order of the phase transition. If the sign problem
occurs at large volume, the Lee-Yang zeros will always approach the real axis
of the complex parameter plane in the thermodynamic limit. This implies that a
scaling behavior which would suggest a crossover transition will not be
obtained. To clarify this problem, we discuss the Lee-Yang zero analysis for
SU(3) pure gauge theory as a simple example without the sign problem, and then
consider the case of non-zero density QCD. It is suggested that the
distribution of the Lee-Yang zeros in the complex parameter space obtained by
each simulation could be more important information for the investigation of
the critical endpoint in the plane than the finite volume scaling
behavior.Comment: 16 pages, 3 figures, 2 tables, minor change
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