1,984 research outputs found
The Role of Color-Magnetic Monopoles in a Gluonic Plasma
The role of color-magnetic monopoles in a pure gauge plasma at high
temperature is considered. In this temperature regime, monopoles can
be considered heavy, rare objects embedded into matter consisting mostly of the
usual "electric" quasiparticles, quarks and gluons. The gluon-monopole
scattering is found to hardly influence thermodynamic quantities, yet it
produces a large transport cross section, significantly exceeding that for pQCD
gluon-gluon scattering up to quite high . This mechanism keeps viscosity
small enough for hydrodynamics to work at LHC.Comment: 4 pages, 4 figures, Talk presented at the Quark Matter 2009
Conference, Knoxville, T
Phases of QCD, Polyakov Loop and Quasiparticles
QCD thermodynamics is studied using a model which combines Polyakov loop
dynamics with spontaneous chiral symmetry breaking and its restoration (the
PNJL model). The input is fixed entirely by pure-gauge lattice QCD results and
by pion properties in vacuum. Successful comparisons with results from thermal
lattice QCD are achieved, including extrapolations to finite quark chemical
potential. The phase diagram and selected susceptibilities for two quark
flavors are investigated with inclusion of diquark degrees of freedom.Comment: 9 pages, 8 figures. To appear in Proceedings YKIS2006, Prog. Theor.
Phys. Suppl. (Kyoto
Real and imaginary-time quarkonium correlators in a hot plasma
The possibility of describing the behavior of a pair in a hot
plasma in terms of an effective potential is investigated. It is shown that as
long as medium effects can be embodied in a gaussian action, like in the QED
case, the propagator obeys a closed temporal evolution equation
whose large-time behavior is governed by an effective potential. The latter,
beside screening, displays also an imaginary part related to collisions.Comment: Talk given at the 8-th Conference "Quark Confinement and the Hadron
Spectrum", Mainz, Germany, 1-6 September 200
Recent thermodynamic results from lattice QCD analyzed within a quasi-particle model
The thermodynamic behavior of QCD matter at high temperature is currently
studied by lattice QCD theory. The main features are the fast rise of the
energy density around the critical temperature and the large
trace anomaly of the energy momentum tensor
which hints at a strongly interacting system. Such features can be accounted
for by employing a massive quasi-particle model with a temperature-dependent
bag constant. Recent lattice QCD calculations with physical quark masses by the
Wuppertal-Budapest group have shown a slower increase of and a
smaller peak with respect to previous results from the
hotQCD collaboration. We investigate the implications of such differences from
the point of view of a quasi-particle model, also discussing light and strange
quark number susceptibilities. Furthermore, we predict the impact of these
discrepancies on the temperature-dependence of the transport properties of
matter, like the shear and bulk viscosities.Comment: 18 pages, 9 figures; version accepted in Phys. Rev.D; calculation
with relaxation time \tau \sim g^4 ln g has been adde
Impact of resonance regeneration and decay on the net-proton fluctuations in a hadron resonance gas
We investigate net-proton fluctuations as important observables measured in
heavy-ion collisions within the hadron resonance gas (HRG) model. Special
emphasis is given to effects which are a priori not inherent in a thermally and
chemically equilibrated HRG approach. In particular, we point out the
importance of taking into account the successive regeneration and decay of
resonances below the chemical freeze-out, which lead to a randomization of the
isospin of nucleons and thus to additional fluctuations in the net-proton
number. We find good agreement between our model results and the recent STAR
measurements of the higher-order moments of the net-proton distribution
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