Higher order cumulants of net baryon-number distributions at non-zero μB\mu_B

Feb 5, 2020

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Abstract: (Elsevier)
Using recent results on higher order cumulants of conserved charge fluctuations from lattice QCD, we construct mean, variance, skewness, kurtosis, hyper-skewness and hyper-kurtosis of net-baryon number distributions for small baryon chemical potentials μ B . For the strangeness neutral case ( μ S = 0) at fixed ratio of electric charge to baryon number density ( nQnB=0.4 ), which is appropriate for a comparison with heavy ion collisions, we present results for κ B σ 2 B , S B σ 3 B / M B , κ H B σ 4 B and S H B σ 5 B / M B on the crossover line for the chiral transition, T pc ( μ B ). Continuum extrapolations for this pseudo-critical transition line have recently been reported by HotQCD up to baryon chemical potentials μ B ≃ 300 MeV [A. Bazavov, et al., Chiral crossover in QCD at zero and non-zero chemical potentials, Phys. Lett. B 795 (2019) 15–21. arXiv:1812.08235 .]. These cumulant ratios are of direct relevance for comparisons with corresponding ratios measured by STAR in the BES-I and II runs at beam energies sNN≥20GeV . In particular, we point out that recent high statistics results on skewness and kurtosis of net-baryon number distributions obtained by STAR at sNN=54.4GeV put strong constraints on freeze-out parameters and are consistent with predictions from thermal QCD.
Note:
  • 4 pages, 6 figures, Contribution to the Quark Matter 2019 Conference Proceedings
  • Lattice QCD
  • Freeze-Out
  • Fluctuations
  • Cumulants
  • potential: chemical
  • charge: conservation law
  • baryon number: density
  • charge: fluctuation
  • transition: chiral
  • charge: electric