Fluctuations of particle ratios as a freeze-out probe

Abstract

We explain how event-by-event fluctuations of particle ratios can constrain and falsify the statistical model of particle production in heavy ion collisions, using $K/\pi$ fluctuations as an example. We define an observable capable of determining which statistical model, if any, governs freeze-out in ultrarelativistic heavy ion collisions. We calculate this observable for $K/\pi$ fluctuations, and show that it should be the same for RHIC and LHC energies, as well as independent of centrality, if the Grand-Canonical statistical model is an appropriate description and chemical equilibrium applies. We describe what happens in case of deviations from this scenario, such as light quark chemical non-equilibrium, strange quark over-saturation and local conservation (canonical ensemble) for strange quarks. We also introduce a similar observable capable, together with the published $K^{\ast }/K$ measurement, of ascertaining if an interacting hadron gas phase governs the system between thermal and chemical freeze-out, and of ascertaining its duration and impact on hadronic chemistry

arXiv commentProceedings for talk given at Strangeness 2007, Levoca, Slovakia

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Cited by in corpus (2)

• K/pi Fluctuations at Relativistic Energies
• Fluctuations of the $K/\pi$ Ratio in Nucleus-Nucleus Collisions: Statistical and Transport Models