Abstract
We present here continuum extrapolated results for all 2nd order cumulants using the most resent results obtained by the HotQCD collaboration in (2+1)-flavor QCD. We constrain the applicability of various HRG models by presenting a detailed comparison of our results based on different sets of hadron spectra as well as with virial expansion based model calculations. A comparison with our lattice QCD results for 2nd order cumulants with models that parametrize repulsive interactions among baryons and anti-baryons in a hadron resonance gas through a single excluded volume parameter (EVHRG) is also shown.
Highlights
The partition function of quantum chromodynamics (QCD) depends on the temperature (T) and the chemical potentials, μB, μQ and μS corresponding to three conserved charges namely baryon number (B), electric charge (Q) and strangeness (S)
It is essential to constrain the applicability of hadron resonance gas (HRG) models by a detailed comparison with lattice QCD, which is the fundamental theory of strong interactions [1]
In these proceedings we present all the 2nd order cumulants calculated by the HotQCD collaboration at vanishing chemical potential in (2+1) flavor QCD and show a detailed comparison with various HRG models
Summary
The partition function of quantum chromodynamics (QCD) depends on the temperature (T) and the chemical potentials, μB, μQ and μS corresponding to three conserved charges namely baryon number (B), electric charge (Q) and strangeness (S). On the other hand two large experimental programs at RHIC in USA and LHC in Switzerland measure the fluctuations of conserved charges either from event by event collisions or from particle yields In those experimental programs the temperature and chemical potential at the time of freeze out is determined by using hadron resonance gas (HRG) models. In HRG model calculations with point like non-interacting resonance the non-strange baryons, strange baryons, pions and kaons provide the major contributions to χ1B1Q , χ1B1S , χ2Q and χ1Q1S respectively We compare these observables with HRG model calculations based on only established resonances (PDGHRG) and it is clear that for all the 2nd order observables PDGHRG works poorly at T > 140 MeV. The temperature derivatives of all cumulants calculated in HRG models are quite different from QCD at T > 156 MeV indicating that a hadronic description of the thermal medium does not seem to be appropriate for temperatures beyond Tpc
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