253 research outputs found
Equation of State and Viscosities from a Gravity Dual of the Gluon Plasma
Employing new precision data of the equation of state of the SU(3) Yang-Mills
theory (gluon plasma) the dilaton potential of a gravity-dual model is adjusted
in the temperature range within a bottom-up approach. The ratio
of bulk viscosity to shear viscosity follows then as for and achieves a maximum value of
at , where is the
non-conformality measure and is the velocity of sound squared, while
the ratio of shear viscosity to entropy density is known as for
the considered set-up with Hilbert action on the gravity side.Comment: 19 pages, 13 figures. Version published in PL
Plasmons, plasminos and Landau damping in a quasiparticle model of the quark-gluon plasma
A phenomenological quasiparticle model is surveyed for 2+1 quark flavors and
compared with recent lattice QCD results. Emphasis is devoted to the effects of
plasmons, plasminos and Landau damping. It is shown that thermodynamic bulk
quantities, known at zero chemical potential, can uniquely be mapped towards
nonzero chemical potential by means of a thermodynamic consistency condition
and a stationarity condition.Comment: Sep. 2007. 13 pp. Invited talk given at Zimanyi 75 Memorial Workshop
on Hadronic and Quark Matter, Budapest, Hungary, 2-4 Jul. 2007; reviewed and
published versio
Plasmons, plasminos and Landau damping in a quasiparticle model of the quark-gluon plasma
A phenomenological quasiparticle model is surveyed for 2+1 quark flavors and
compared with recent lattice QCD results. Emphasis is devoted to the effects of
plasmons, plasminos and Landau damping. It is shown that thermodynamic bulk
quantities, known at zero chemical potential, can uniquely be mapped towards
nonzero chemical potential by means of a thermodynamic consistency condition
and a stationarity condition.Comment: Sep. 2007. 13 pp. Invited talk given at Zimanyi 75 Memorial Workshop
on Hadronic and Quark Matter, Budapest, Hungary, 2-4 Jul. 2007; reviewed and
published versio
Cross-over versus first-order phase transition in holographic gravity-single-dilaton models of QCD thermodynamics
A dilaton potential is adjusted to recently confirmed lattice QCD
thermodynamics data in the temperature range where is the pseudo-critical temperature. The employed holographic
model is based on a gravity--single-field dilaton dual. We discuss conditions
for enforcing (for the pure gluon plasma) or avoiding (for the QCD quark-gluon
plasma) a first-order phase transition, but still keeping a softest point
(minimum of sound velocity).Comment: 11 pages, 9 figure
Gluon Emission of Heavy Quarks: Dead Cone Effect
The lowest-order induced soft gluon radiation processes of heavy quarks have
been analyzed to quantify the dead cone effect. This effect is most likely
expected to suppress significantly the energy loss of charm quarks passing an
amorphous color-neutral deconfined medium, as has been concluded from recent
experiments at RHIC
Impact of Four-Quark Condensates on In-Medium Effects of Hadrons
Spectral properties of hadrons in nuclear matter are treated in the framework
of QCD sum rules. The influence of the ambient strongly interacting medium is
encoded in various condensates. Especially, the structure of different
four-quark condensates and their density dependencies in light quark systems
are exemplified for the omega meson and the nucleon.Comment: Contribution to Quark Confinement and the Hadron Spectrum VII,
02.-07.09.2006, Ponta Delgada, Portuga
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