PUB - Publikationen an der Universität Bielefeld

We present some lattice QCD results on first (chi(i)(1)) and second (chi(i)(2)) cumulants of and correlations (chi(ij)(11)) among net baryon-number (B), strangeness (S) and electric charge (Q) along the pseudocritical line [T-pc(mu(B))] in the temperature (T)-baryon chemical potential (mu(B)) phase diagram of (2+1)-flavor QCD. We point out that violations of sum rules among second order cumulants, which hold in the isospin symmetric limit of vanishing electric charge chemical potential, are small along the T-pc(mu(B)) for the entire range of mu(B) covered in the RHIC beam energy scan. For the strangeness neutral matter produced in heavy-ion collisions this leads to a close relation between chi(BS)(11) and chi(QS)(11). We compare lattice QCD results for chi(BS)(11)/chi(S)(2) along the T-pc(mu(B)) line with preliminary experimental measurements of chi(BS)(11)/chi(S)(2) for collision energies 7.7 GeV <= root s(NN) <= 62.4 GeV. While we find good agreements for root s(NN) >= 39 GeV, differences are sizeable at smaller values of root s(NN). Moreover, we compare lattice QCD results for the ratio of the strangeness (mu(S)) to baryon (mu(B)) chemical potentials, which define a strangeness neutral system with fixed electric charge to baryon number density, with experimental results obtained by the STAR collaboration for mu(S)/mu(B) using strange baryon yields on the freeze-out line. Finally, we determine the baryon chemical potential at the freeze-out (mu(f)(B)) by comparing chi(B)(1)/chi(B)(2) along the T-pc(mu(B)) with the experimentally measured net-proton cumulants chi(p)(1)/chi(p)(2). We find that {mu(f)(B), T-pc(mu(f)(B))} are consistent with the freeze-out parameters of the statistical-model fits to experimentally measured hadron yields for root s(NN) >= 11.5 GeV.