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Equation of State for the Two-component Van der Waals Gas with Relativistic Excluded Volumes

G. Zeeb·K. A. Bugaev·P. T. Reuter·H. Stocker
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Abstract

A canonical partition function for the two-component excluded volume model is derived, leading to two different van der Waals approximations. The one is known as the Lorentz-Berthelot mixture and the other has been proposed recently. Both models are analysed in the canonical and grand canonical ensemble. In comparison with the one-component van der Waals excluded volume model the suppression of particle densities is reduced in these two-component formulations, but in two essentially different ways. Presently used multi-component models have no such reduction. They are shown to be not correct when used for components with different hard-core radii. For high temperatures the excluded volume interaction is refined by accounting for the Lorentz contraction of the spherical excluded volumes, which leads to a distinct enhancement of lighter particles. The resulting effects on pion yield ratios are studied for AGS and SPS data.

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G. Zeeb, K. A. Bugaev, P. T. Reuter, H. Stocker. 2002-09-03. Equation of State for the Two-component Van der Waals Gas with Relativistic Excluded Volumes. https://arxiv.org/abs/nucl-th/0209011

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