QCD bulk thermodynamics and conserved charge fluctuations with HISQ fermions

Abstract

After briefly reviewing recent progress by the HotQCD collaboration in studying the 2+1 flavor QCD equation of state, we will focus on results on fluctuations of conserved charges by the BNL-Bielefeld and HotQCD collaborations. Higher order cumulants of the net-charge distributions are increasingly dominated by a universal scaling behavior, which arises due to a critical point of QCD in the chiral limit. Considering cumulants up to the 6^{th} order, we observe that they generically behave as expected from universal scaling laws, which is quite different from cumulants calculated within the hadron resonance gas model. Taking ratios of these cumulants, we obtain volume independent results that can be compared to the experimental measurements. We will argue that the freeze-out chemical potentials and the freeze-out temperature, usually obtained by a HRG model fit to the measured hadronic yields, can also be obtained in a model independent way from ab-initio lattice QCD calculations by utilizing observables related to conserved charge fluctuations. Further, we will show that the freeze-out strangeness and electric charge chemical potentials can be fixed by imposing strangeness neutrality and isospin asymmetry constraints in the lattice QCD calculations, in order to accommodate conditions met in heavy ion collisions. All results have been obtained with the highly improved staggered quark action (HISQ) and almost physical quark masses on lattices with temporal extent of N_τ=6,8,10,12.

10 pages, 6 figures, contribution to the proceedings of Extreme QCD 2012, August 21-23, Washington DC, USA

References in corpus (7)

• Viscosity Information from Relativistic Nuclear Collisions: How Perfect is the Fluid Observed at RHIC?
• The QCD equation of state with dynamical quarks
• Highly Improved Staggered Quarks on the Lattice, with Applications to Charm Physics
• Freeze-out Conditions in Heavy Ion Collisions from QCD Thermodynamics
• The phase boundary for the chiral transition in (2+1)-flavor QCD at small values of the chemical potential
• Initial state fluctuations and higher harmonic flow in heavy-ion collisions
• The QCD equation of state with 2+1 flavors of Highly Improved Staggered Quarks (HISQ)

Cited by in corpus (8)

• Equation of State of hot and dense QCD: Resummed perturbation theory confronts lattice data
• Neutron star structure from QCD
• Review of recent highlights in lattice calculations at finite temperature and finite density
• From Heavy-Ion Collisions to Compact Stars: Equation of State and Relevance of the System Size
• The Debye Length and the Running Coupling of QCD: a Potential and Phenomenological Approach
• Probing the finite density equation of state of QCD via resummed perturbation theory
• Kurtoses and high order cumulants: Insights from resummed perturbation theory
• Conserved charge fluctuations with HISQ fermions