Conserved Charge Fluctuations from Lattice QCD and the Beam Energy Scan

Karsch F, Bazavov A, Ding H-T, et al. Conserved Charge Fluctuations from Lattice QCD and the Beam Energy Scan. Nuclear Physics A. 2016;956:352-355.We discuss the next-to-leading order Taylor expansion of ratios of cumulants of net-baryon number fluctuations. We focus on the relation between the skewness ratio, S-B sigma(B) = chi(B)(3)/chi(B)(1) and the kurtosis ratio, KBol = chi(B)(4)/chi(B)(4). We show that differences in these two cumulant ratios are small for small values of the baryon chemical potential. The next-to-leading order correction to kappa(B)sigma(2)(B) however is approximately three times larger than that for S-B sigma(B). The former thus drops much more rapidly with increasing beam energy, root S-NN. We argue that these generic patterns are consistent with current data on cumulants of net-proton number fluctuations measured by the STAR Collaboration at root(SNN) >= 19.6 GeV