Has Tc been measured by heavy ion experiments?

Abstract

We discuss the role of cumulants of net baryon number fluctuations in the analysis of critical behavior in QCD and the study of freeze-out conditions in heavy ion experiments. Through the comparison of the current set of measurements of higher order cumulants of net baryon number fluctuations with lattice QCD calculations and results from hadron resonance gas model we can learn to what extent freeze-out as, determined by such cumulants, occurs close to the QCD transition temperature and thus can probe critical behavior at small values of the baryon chemical potential. Understanding how the relation between freeze-out conditions and the QCD crossover transition is reflected in properties of the experimentally determined cumulants is an important prerequisite to search for the QCD critical point. We point out that even if perfect continuum extrapolated lattice QCD results would be available, it would be inappropriate to use these observables to extract the value of the QCD transition temperature at vanishing baryon chemical potential from experimental data. We furthermore provide indications that a recently performed comparison of lattice QCD results on cumulants with data from heavy ion experiments suffer from systematic as well as statistical uncertainties in the lattice QCD calculations. This makes such comparison of lattice QCD calculations with experimental data at present not useful.

9 pages, 3 EPS files

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• Scale for the Phase Diagram of Quantum Chromodynamics
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Cited by in corpus (18)

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• Net-charge probability distributions in heavy ion collisions at chemical freeze-out
• Large proton cumulants from the superposition of ordinary multiplicity distributions
• Baryon number fluctuations in the 2+1 flavor low energy effective model
• Mapping the QCD phase diagram with statistics friendly distributions
• Centrality dependence of chemical freeze-out parameters from net-proton and net-charge fluctuations using hadron resonance gas model
• Higher order net-proton number cumulants dependence on the centrality definition and other spurious effects
• Nuclear interactions and net-proton number fluctuations in heavy ion collisions at the SIS18 accelerator
• Dynamical development of proton cumulants and correlation functions in Au+Au collisions at $\sqrt{s_{NN}}=7.7$ GeV from a multiphase transport model
• Finite Volume Cumulant Expansion in QCD-Colorless Plasma
• Factorial cumulants from global baryon number conservation
• Factorial cumulants from short-range correlations and global baryon number conservation
• Net-baryon multiplicity distribution consistent with lattice QCD
• A short introduction to heavy-ion physics
• Probing fluctuations and correlations of strangeness by net-kaon cumulants in Au+Au collisions at $\sqrt{s_{NN}}=7.7$ GeV
• Cumulants from short-range correlations and baryon number conservation - next-to-leading order