323 research outputs found
Lattice Regularized QCD at Finite Temperature
During the first part of this review we will focus on the thermodynamics of
gauge theories at finite temperature. We will present results from a
calculation of electric and magnetic screening masses for the gluons, discuss
calculations of the critical temperature in units of the string tension and
bulk thermodynamic quantities like the energy density and pressure. In
particular, the latter calculations have now reached a stage where
cut-off effects can be controlled systematically and an extrapolation to the
continuum limit can be performed. In the second part we discuss the critical
behaviour of QCD with light quarks. We analyze the chiral transition in
2-flavour QCD and present results on the temperature dependence of hadron
properties.Comment: 20 pages, 13 Postscript figure
Fluctuations of Goldstone modes and the chiral transition in QCD
We provide evidence for the influence of thermal fluctuations of Goldstone
modes on the chiral condensate at finite temperature. We show that at fixed
temperature, T<Tc, in the vicinity of the chiral transition temperature this
leads to a characteristic dependence of the chiral condensate on the square
root of the light quark mass (m_l), which is expected for 3-dimensional models
with broken O(N) symmetry. As a consequence the chiral susceptibility shows a
strong quark mass dependence for all temperatures below Tc and diverges like
1/sqrt(m_l) in the chiral limit.Comment: 4 pages,presented in Strong and ElectroWeak Matter, August 2008,
Amsterdam, The Netherland
Thermodynamics of 2 and 3 flavour QCD
We discuss recent results on the thermodynamics of QCD in the presence of
light dynamical quark degrees of freedom. In particular, we concentrate on an
analysis of the flavour and quark mass dependence of the QCD phase diagram, the
equation of state and the transition temperature. Moreover, we present recent
results on the heavy quark free energy.Comment: 10 pages, To appear in the proceedings of QCD@Work: International
Conference on QCD: Theory and Experiment, Martina Franca, Italy, 16-20 Jun
200
Lattice Simulations of the Thermodynamics of Strongly Interacting Elementary Particles and the Exploration of New Phases of Matter in Relativistic Heavy Ion Collisions
At high temperatures or densities matter formed by strongly interacting
elementary particles (hadronic matter) is expected to undergo a transition to a
new form of matter - the quark gluon plasma - in which elementary particles
(quarks and gluons) are no longer confined inside hadrons but are free to
propagate in a thermal medium much larger in extent than the typical size of a
hadron. The transition to this new form of matter as well as properties of the
plasma phase are studied in large scale numerical calculations based on the
theory of strong interactions - Quantum Chromo Dynamics (QCD). Experimentally
properties of hot and dense elementary particle matter are studied in
relativistic heavy ion collisions such as those currently performed at the
relativistic heavy ion collider (RHIC) at BNL. We review here recent results
from studies of thermodynamic properties of strongly interacting elementary
particle matter performed on Teraflops-Computer. We present results on the QCD
equation of state and discuss the status of studies of the phase diagram at
non-vanishing baryon number density.Comment: 10 pages, invited plenary talk given at the conference 'Scientific
Discovery through Advanced Computing', SciDAC 2006, June 25-29, Denver, US
Deconfinement and Quarkonium Suppression
Modifications in the production pattern of heavy quark bound states have long
been considered to provide sensitive signatures for the thermal properties of
dense matter created in heavy ion collisions. The original concept of Matsui
and Satz for quarkonium suppression as signature for deconfinement in heavy ion
collisions has been challenged recently through lattice studies of spectral
functions, which indicate the persistence of heavy quark bound states at
temperatures well above the transition, as well as through the refined analysis
of hadronization and recombination models, which take into account the thermal
evolution of the medium generated in a heavy ion collision. We will review here
recent developments on these topics.Comment: 10 pages, contribution to the proceedings of Hard Probes 2004,
International Conference on Hard and Electromagnetic Probes of High Energy
Nuclear Collisions, Nov. 4-10, 2004, Ericeira, Portugal, references update
O(N) universality and the chiral phase transition in QCD
We discuss universal scaling properties of (2+1)-flavor QCD in the vicinity
of the chiral phase transition at vanishing as well as non-vanishing light
quark chemical potential (mu_l). We provide evidence for O(N) scaling of the
chiral order parameter in (2+1)-flavor QCD and show that the scaling analysis
of its derivative with respect to the light quark chemical potential provides a
unique approach to the determination of the curvature of the chiral phase
transition line in the vicinity of mu_l/T=0.Comment: 6 pages, 6 EPS-files; talk presented at the International Workshop
'New Frontiers in QCD 2010' at the Yukawa Institute for Theoretical Physics,
Kyoto, Japan, March 1-1
QCD thermodynamics in the crossover/freeze-out region
We use results from a 6-th order Taylor expansion of the QCD equation of
state to construct expansions for cumulants of conserved charge fluctuations
and their correlations. We show that these cumulants strongly constrain the
range of applicability of hadron resonance gas model calculations. We point out
that the latter is inappropriate to describe equilibrium properties of QCD at
zero and non-zero values of the baryon chemical potential already at T~155 MeV.Comment: 5 pages, 6 figures, contribution to the International Conference
"Critical Point and Onset of Deconfinement 2016", Wroc{\l}aw, Poland, May
30th - June 4th, 201
Lattice QCD at High Temperature and the QGP
We review recent progress in studies of bulk thermodynamics of strongly
interacting matter, present results on the QCD equation of state and discuss
the status of studies of the phase diagram at non-vanishing quark chemical
potential.Comment: 9 pages, plenary talk given at PANIC05, Particles and Nuclei
International Conference, Santa Fe, NM, Oct. 24-28, 200
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