Speaker
Description
In this talk we present a generalization of the multicomponent Van der Waals equation of state in the grand canonical ensemble [1, 2]. For the one-component case the third and fourth virial coefficients are calculated analytically. It is shown that an adjustment of a single model parameter allows us to reproduce the third and fourth virial coefficients of the gas of hard spheres with small deviations from their exact values. A thorough comparison of the compressibility factor and speed of sound of this model with the one and two component Carnahan-Starling equation of state is made. We show that the model with the induced surface tension can reproduce the results of the Carnahan-Starling equation of state up to the packing fractions 0.2-0.22 at which the Van der Waals equation of state is inapplicable [1]. Using this approach we develop an entirely new hadron resonance gas model and apply it to a description of the hadron yield ratios measured at AGS, SPS, RHIC and ALICE energies of nuclear collisions. We confirm that the strangeness enhancement factor has a peak at low AGS energies and that there is a jump of chemical freeze-out temperature between two highest AGS energies [1, 2]. Also we argue that the chemical equilibrium of strangeness, i.e. γs ≃ 1, observed above the center of mass collision energy 8.7 GeV may be related to a hadronization of quark gluon bags which have the Hagedorn mass spectrum, and, hence, it may be a new signal for the onset of deconfinement.
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K. A. Bugaev, V. V. Sagun, A. I. Ivanytskyi, I. P. Yakimenko, E. G. Nikonov, A.V. Taranenko and G. M. Zinovjev, Nucl. Phys. A 970, (2018) 133.
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K. A. Bugaev, R. Emaus, V.V. Sagun, A. I. Ivanytskyi, L. V. Bravina, D. B. Blaschke, E. G. Nikonov, A. V. Taranenko, E. E. Zabrodin and G. M. Zinovjev, Phys. Part. Nucl. Lett. 15, (2018) 210.
