Off-diagonal correlators of conserved charges from lattice QCD and how to relate them to experiment

Abstract

Like fluctuations, non-diagonal correlators of conserved charges provide a tool for the study of chemical freeze-out in heavy ion collisions. They can be calculated in thermal equilibrium using lattice simulations, and be connected to moments of event-by-event net-particle multiplicity distributions. We calculate them from continuum extrapolated lattice simulations at ${\mu }_B=0$, and present a finite-${\mu }_B$ extrapolation, comparing two different methods. In order to relate the grand canonical observables to the experimentally available net-particle fluctuations and correlations, we perform a Hadron Resonance Gas (HRG) model analysis, which allows us to completely break down the contributions from different hadrons. We then construct suitable hadronic proxies for fluctuations ratios, and study their behavior at finite chemical potentials. We also study the effect of introducing acceptance cuts, and argue that the small dependence of certain ratios on the latter allows for a direct comparison with lattice QCD results, provided that the same cuts are applied to all hadronic species. Finally, we perform a comparison for the constructed quantities for experimentally available measurements from the STAR Collaboration. Thus, we estimate the chemical freeze-out temperature to 165 MeV using a strangeness-related proxy. This is a rather high temperature for the use of the Hadron Resonance Gas, thus, further lattice studies are necessary to provide first principle results at intermediate ${\mu }_B$.

20 pages, 17 figures, 1 table, version published in Phys.Rev.D

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Cited by in corpus (7)

• Second order cumulants of conserved charge fluctuations revisited I. Vanishing chemical potentials
• Search for the QCD Critical Point in High Energy Nuclear Collisions
• New approach to lattice QCD at finite density; results for the critical end point on coarse lattices
• Particlization of an interacting hadron resonance gas with global conservation laws for event-by-event fluctuations in heavy-ion collisions
• Critical lensing and kurtosis near a critical point in the QCD phase diagram in and out-of-equilibrium
• Constraining the hadronic spectrum and repulsive interactions in a hadron resonance gas via fluctuations of conserved charges
• Smooth matching of $\hat{q}$ from hadronic to quark and gluon degrees of freedom