Equation of State from Lattice QCD Calculations (original) (raw)
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Transition temperature and the equation of state from lattice QCD, Wuppertal-Budapest results
Journal of Physics: Conference Series, 2011
The QCD transition is studied on lattices up to N t = 16. The chiral condensate is presented as a function of the temperature, and the corresponding transition temperature is extracted. The equation of state is determined on lattices with N t = 6, 8, 10 and at some temperature values with N t = 12. The pressure and the trace anomaly are presented as functions of the temperature in the range 100 ...1000 MeV . Using the same configurations we determine the continuum extrapolated phase diagram of QCD on the µ − T plane for small to moderate chemical potentials. Two transition lines are defined with two quantities, the chiral condensate and the strange quark number susceptibility.
Results for the equation of state in 2+1 flavor QCD at zero net baryon density using the Highly Improved Staggered Quark (HISQ) action by the HotQCD collaboration are presented. The strange quark mass was tuned to its physical value and the light (up/down) quark masses fixed to m l = 0.05m s corresponding to a pion mass of 160 MeV in the continuum limit. Lattices with temporal extent N t = 6, 8, 10 and 12 were used. Since the cutoff effects for N t > 6 were observed to be small, reliable continuum extrapolations of the lattice data for the phenomenologically interesting temperatures range 130MeV < T < 400MeV could be performed. We discuss statistical and systematic errors and compare our results with other published works.
2005
I present our recent results on the critical end point in the \mu_B-T phase diagram of QCD with two flavours of light dynamical quarks and compare them with similar results from other groups. Implications for a possible energy scan at the RHIC are discussed. I also comment briefly on the new results of great relevance to heavy ion collisions from finite temperature lattice QCD simulations on speed of sound, specific heat and on the fate of J/\psi.
PoS (LAT2009) 175 The QCD equation of state and transition at finite temperature
2009
Among the most important and fundamental problems in finite-temperature QCD are the calculation of the bulk properties of hot QCD matter and the characterization of the nature of the QCD phase transition. Understanding finite temperature QCD also has direct application in interpreting the results from heavy ion collision experiments. Here, we present a lattice calculation of the QCD equation of state, ie, the pressure, energy density, entropy density, and speed of sound, at finite temperature and vanishing chemical potential. We also ...
Computational Aspects of Lattice QCD
2003
Monte Carlo simulations applied to the lattice formulation of quantum chromodynamics (QCD) enable a study of the theory from first principles, in a nonperturbative way. After over two decades of developments in the methodology for this study and with present-day computers in the teraflops range, lattice-QCD simulations are now able to provide quantitative predictions with errors of a few percent. This means that these simulations will soon become the main source of theoretical results for comparison with experiments in physics of the strong interactions. It is therefore an important moment for the beginning of Brazilian participation in the field.
Equation of state and QCD transition at finite temperature
Physical Review D, 2009
We calculate the equation of state in 2+1 flavor QCD at finite temperature with physical strange quark mass and almost physical light quark masses using lattices with temporal extent Nt=8. Calculations have been performed with two different improved staggered fermion actions, the asqtad and p4 actions. Overall, we find good agreement between results obtained with these two O(a^2) improved staggered fermion discretization schemes. A comparison with earlier calculations on coarser lattices is performed to quantify systematic errors in current studies of the equation of state. We also present results for observables that are sensitive to deconfining and chiral aspects of the QCD transition on Nt=6 and 8 lattices. We find that deconfinement and chiral symmetry restoration happen in the same narrow temperature interval. In an Appendix we present a simple parametrization of the equation of state that can easily be used in hydrodynamic model calculations. In this parametrization we also incorporated an estimate of current uncertainties in the lattice calculations which arise from cutoff and quark mass effects. We estimate these systematic effects to be about 10 MeV