QCD thermodynamics from lattice simulations an update using finer lattice spacings Péter Petreczky Physics Department and RIKEN-BNL

WWND, February 2-7, 2009

• Equation of State calculations for

• Chiral and deconfinement transition temperature in QCD

• Fluctuations of conserved charges and deconfinement

• Spatial correlation functions and the nature of the deconfined phase at high temperatures

• Summary

Collaboration and computational resources

RBC-Bielefeld Collaboration (p4 action) :

Hot QCD Collaboration (p4 and asqtad actions ) : A. Bazavov, T. Bhattacharya, M. Cheng, N. Christ, C. DeTar, S. Ejiri, S. Gottlieb, R. Gupta, U. Heller, K. Huebner, C. Jung, F. Karsch, E. Laermann, L. Levkova, T. Luu, R. Mawhinney, C. Miao, P. Petreczky, D. Renfrew, C. Schmidt, R. Soltz, W. Soeldner, R. Sugar, D. Toussaint, P. Vranas

M. Cheng S. Ejiri, F. Karsch, C. Jung, C. Miao, P. Petreczky (BNL), N. Christ, R. Mawhiney (Columbia) O. Kaczmarek, E. Laermann, S. Mukherjee C. Schmidt (Bielefeld), W. Soeldner (GSI)Former members : S. Datta, J. van der Heide, K. Huebner, J. Liddle, K. Petrov, C. Pica, T. Umeda

The use of improved staggered fermion actions is crucial !

Lattice results on trace anomaly

Pressure, energy density and speed of sound

rapid rise in number of d.o.f at T=180-200 MeV

10-15% deviation from the ideal gas limit

lattice discretization errors are small

rise in the entropy and energy density happens in the same temperature interval where the rapid change of the chiral condensate and Polyakov loop takes place

Deconfinement and chiral transition

Fluctuations of conserved charges

Fluctuations in the hadron resonance gas model

Fluctuations of conserved charges at high T

1) Strangeness fluctuations are suppressed relative of the light (u,d) quark number fluctuations at low T (strange hadrons are heavier). 2) For T>300MeV there is no difference in fluctuation of strange and light quark number. 3) In the intermediate T-region strangeness fluctuations are still suppressed and the amount of suppression cannot be understoodas a quark mass difference.

The quark number susceptibilitiesare close to the SB limit for T>300MeVin agreement with resummed petrurbativepredictions and in contrrast with expectations based on the strong couplinglimit of N=4 SYM in AdS/CFT

Static quark anti-quark free energy in QCD

preliminary

Temporal Wilson line:

Mócsy, P.P., PRL 99 (07) 211602

Spatial string tension at T>0

non-perturbative

calculated perturbatively

Spatial correlators at T>0

Summary

• Calculations of thermodynamic quantities have been extended to lattices with temporal extent . Comparison with previous results as well as with asqtad actionshows no significant cutoff effects in the high-T region

• Study of fluctuations shows that quantum numbers are carried by weakly interacting quarksfor . This picture is also supported by calculation of spatial meson correlators

• In the temperature region lattice calculations of the trace anomaly, fluctuations of conserved charges and spatial meson correlation function indicate the strongly interacting nature of the deconfined phase

• Strong color screening in the deconfined phase leads to quarkonium melting abovedeconfinement

• At high temperatures non-perturbative effects are due to soft chromo-magnetic fields