PUB - Publikationen an der Universität Bielefeld

We discuss recent results on fluctuations of conserved charges, and theirapproach to the hadron resonance gas at temperatures below the chiral crossover(Tc) as well as to a gas of free quarks at very high temperatures. We willfocus on the strange degrees of freedom and verify that they are consistentwith those of an uncorrelated gas of hadrons for temperatures of T<160 MeV andthat they can be described by a quasi particle model at best for T>2Tc. Toextract this information we use all cumulants of net baryon number and netstrangeness fluctuations and their correlations up to the fourth order. Inparticular we propose observables that serve as indicator for the validity ofthe hadronic degrees of freedom and show that the partial pressures fromdifferent strangeness sectors agree separately with HRG model predictions.