We present results for the ratios of mean (MB), variance (sigma(2)(B)), skewness (SB) and kurtosis(kappa B) of net baryon-number fluctuations obtained in lattice QCD calculations with physical values of light… Click to show full abstract
We present results for the ratios of mean (MB), variance (sigma(2)(B)), skewness (SB) and kurtosis(kappa B) of net baryon-number fluctuations obtained in lattice QCD calculations with physical values of light and strange quark masses. Using next-to-leading order Taylor expansions in baryon chemical potential we find that qualitative features of these ratios closely resemble the corresponding experimentally measured cumulant ratios of net proton-number fluctuations for beam energies down to root s(NN) >= 19.6 GeV. We show that the difference in cumulant ratios for the mean net baryon-number, M-B/sigma(2)(B) = chi(1)(B) (T, mu(B)) / chi(2)(B) (T, mu(B)), and the normalized skewness, S-B sigma(B) = chi(B)(3) (T, mu(B)) / chi(B)(2) (T, mu B), naturally arises in QCD thermodynamics. Moreover, we establish a close relation between skewness and kurtosis ratios, S-B sigma(3)(B) / M-B = chi(B)(3) (T, mu(B)) / chi(B)(1) (T, mu(B)) and kappa(B)sigma(2)(B) = chi(B)(4) (T, mu(B)) /chi(B)(2) (T, mu(B)), valid at small values of the baryon chemical potential.
               
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