Multicomponent van der Waals Model of a Nuclear Fireball in the Freeze-Out Stage

  • Yaroslav D. Krivenko-Emetov National Technical University of Ukraine «Igor Sikorsky Kyiv Polytechnic Institute», Kyiv, Ukraine
Keywords: multicomponent hadron gas, fireball, freeze-out, van derWaals equation, effective nuclear capability, grand canonical ensemble, pressure fluctuation, quark-gluon plasma, experimental data


A model of a two-component van der Waals gas is proposed to describe the hadronic stages of nuclear
fireball evolution during the cooling phase. During the initial stage of hadronization, when mesons are
dominant, a two-component meson model (π0 and π+ mesons) with an effective two-particle interaction
potential in the form of a rectangular well is suggested. In the later stages of hadronization, when almost all
mesons have decayed, a two-component nucleon model consisting of protons and neutrons is proposed,
incorporating the corresponding effective rectangular nucleon potential. The saddle point method has been
utilized for analytical computations of the partition function. This approach has facilitated the consistent
derivation of analytical expressions for both pressure and density, considering the finite dimensions of the
system, as well as analytical expressions for chemical potentials. It is envisaged that the proposed models
and resulting equations can be employed for analyzing experimental data related to the quantitative
attributes of particle yields of various types in the final state arising from the hadronic stages of nuclear
fireball evolution. Additionally, these models can aid in determining the critical parameters of the system
during high-energy nucleus-nucleus collisions. It is demonstrated that in the single-component case, the
model’s results for the baryonic chemical potential correlate with calculations by other authors.


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