Recent results on QCD thermodynamics: lattice QCD versus Hadron Resonance Gas model (original) (raw)
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Hadron resonance mass spectrum and lattice QCD thermodynamics
European Physical Journal C, 2003
We confront lattice QCD results on the transition from the hadronic phase to the quark-gluon plasma with hadron resonance gas and percolation models. We argue that for TleqTmathrmcT\leq T_{\mathrm{c}}TleqTmathrmc the equation of state derived from Monte Carlo simulations of (2+1) quark-flavor QCD can be well described by a hadron resonance gas. We examine the quark mass dependence of the hadron spectrum on the lattice and discuss its description in terms of the MIT bag model. This is used to formulate a resonance gas model for arbitrary quark masses which can be compared to lattice calculations. We finally apply this model to the analysis of the quark mass dependence of the critical temperature obtained in lattice calculations. We show that the value of TmathrmcT_{\mathrm{c}}Tmathrmc for different quark masses agrees with lines of constant energy density in a hadron resonance gas. For large quark masses a corresponding contribution from a glueball resonance gas is required.
QCD transition temperature: full staggered result
2010
We conclude our investigations on the QCD cross-over transition temperatures with 2+1 staggered flavours and one-link stout improvement. We extend our previous two studies [Phys. Lett. B643 (2006) 46, JHEP 0906:088 (2009)] by choosing even finer lattices (N t =16) and we work again with physical quark masses. These new results [for details see JHEP 1009:073,2010] support our earlier findings. We compare them with the published results of the hotQCD collaboration. All these results are confronted with the predictions of the Hadron Resonance Gas model and Chiral Perturbation Theory for temperatures below the transition region. Our results can be reproduced by using the physical spectrum. The findings of the hotQCD collaboration can be recovered only by using a distorted spectrum. This analysis provides a simple explanation for the observed discrepancy in the transition T between our and the hotQCD collaborations.
The QCD transition temperature: Results with physical masses in the continuum limit
Physics Letters B, 2006
The transition temperature (T c ) of QCD is determined by Symanzik improved gauge and stout-link improved staggered fermionic lattice simulations. We use physical masses both for the light quarks (m ud ) and for the strange quark (m s ). Four sets of lattice spacings (N t =4,6,8 and 10) were used to carry out a continuum extrapolation. It turned out that only N t =6,8 and 10 can be used for a controlled extrapolation, N t =4 is out of the scaling region. Since the QCD transition is a non-singular cross-over there is no unique T c . Thus, different observables lead to different numerical T c values even in the continuum and thermodynamic limit. The peak of the renormalized chiral susceptibility predicts T c =151 MeV, wheres T c -s based on the strange quark number susceptibility and Polyakov loops result in 24(4) MeV and 25(4) MeV larger values, respectively. Another consequence of the cross-over is the non-vanishing width of the peaks even in the thermodynamic limit, which we also determine. These numbers are attempted to be the full result for the T =0 transition, though other lattice fermion formulations (e.g. Wilson) are needed to cross-check them.
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.
Thermodynamics of One-flavour QCD
1998
We give a brief introduction on finite temperature phase transitions in lattice QCD including a discussion on the identification of first order transitions. We present a study of the deconfinement phase transition of one-flavour QCD, using the multiboson algorithm on lattice of sizes 8 3 , 12 3 and 16 3 × 4. For heavy quarks our results are characteristic of a first order phase transition which gets weaker as the quark mass decreases and ends at a critical value of κ ∼ 0.1 or in physical units at about 1.6 GeV.
QCD Thermodynamics with an Almost Realistic Quark Mass Spectrum
2005
We will report on the status of a new large scale calculation of thermodynamic quantities in QCD with light up and down quarks corresponding to an almost physical light quark mass value and a heavier strange quark mass. These calculations are currently being performed on the QCDOC Teraflops computers at BNL. We will present new lattice calculations of the transition temperature and various susceptibilities reflecting properties of the chiral transition. All these quantities are of immediate interest for heavy ion phenomenology.
PoS (LAT2009) 175 The QCD equation of state and transition at finite temperature
2009
We present the latest results for the equation of state and the crossover transition in 2+1 flavor QCD from the HotQCD Collaboration. Bulk thermodynamic quantities -energy density, pressure, entropy density, and the speed of sound -are calculated on lattices with temporal extent N t = 8 in the temperature range 140 MeV < T < 540 MeV. We utilize two improved staggered fermion actions, asqtad and p4, with the mass for the two degenerate light quarks chosen to be m ud = 0.1m s , corresponding to m π ≈ 220 MeV for the lightest pion. We also calculate observables that are sensitive to the chiral and deconfing transitions -the light and strange quark number susceptibilities, the chiral condensate, and the renormalized Polyakov loop -finding that deconfinement and chiral symmetry restoration occur in the same narrow temperature interval.
Journal of High Energy Physics, 2010
The present paper concludes our investigations on the QCD cross-over transition temperatures with 2+1 staggered flavours and one-link stout improvement. We extend our previous two studies [Phys. Lett. B643 (2006) 46, JHEP 0906:088 (2009)] by choosing even finer lattices (N t =16) and we work again with physical quark masses. The new results on this broad cross-over are in complete agreement with our earlier ones. We compare our findings with the published results of the hotQCD collaboration. All these results are confronted with the predictions of the Hadron Resonance Gas model and Chiral Perturbation Theory for temperatures below the transition region. Our results can be reproduced by using the physical spectrum in these analytic calculations. The findings of the hotQCD collaboration can be recovered by using a distorted spectrum which takes into account lattice discretization artifacts and heavier than physical quark masses. This analysis provides a simple explanation for the observed discrepancy in the transition temperatures between our and the hotQCD collaborations.
Mott-hadron resonance gas and lattice QCD thermodynamics
Physics of Particles and Nuclei, 2015
We present an effective model for the generic behaviour of hadron masses and phase shifts at finite temperature which shares basic features with recent developments within the PNJL model for correlations in quark matter. On this basis we obtain the transition between a hadron resonance gas phase and the quark gluon plasma in the spirit of the generalized Beth-Uhlenbeck approach where the Mott dissociation of hadrons is encoded in the hadronic phase shifts. Here we restrict ourselves to low-lying hadronic channels and perform a discussion of recent lattice QCD thermodynamics results from this perspective. We find agreement in the asymptotic regions while for the description of the transition itself the inclusion of further hadronic channels as well as a selfconsistent determination of the continuum thresholds is required.
Critical temperature in QCD with two flavors of dynamical quarks
Proceedings of XXIIIrd International Symposium on Lattice Field Theory — PoS(LAT2005)
We present results obtained in QCD with two flavors of non-perturbatively improved Wilson fermions at finite temperature on 16 3 × 8 and 24 3 × 10 lattices. We determine the transition temperature in the range of quark masses 0.6 < m π /m ρ < 0.8 at lattice spacing a≈0.1 fm and extrapolate the transition temperature to the continuum and to the chiral limits. We also discuss the order of phase transition.