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Equation of State of an Interacting Pion Gas with Realistic $π$--$π$ Interactions

R. Rapp·J. Wambach
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Abstract

Within the finite-temperature Greens-function formalism we study the equation of state of a hot interacting pion gas at zero chemical potential. Employing realistic $ππ$ meson-exchange interactions we selfconsistently calculate the in-medium single-pion selfenergy and the $ππ$ scattering amplitude in the quasiparticle approximation. These quantities are then used to evaluate the thermodynamic potential, $Ω_π$(T), from which the state variables: pressure-, entropy- and energy-density can be derived. In contrast to earlier calculations based on the low-energy Weinberg Lagrangian we find an overall increase as compared to the free-gas results. We also consider the possibility of a dropping $ρ$-meson mass as suggested by the 'Brown-Rho Scaling' law.

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R. Rapp, J. Wambach. 1995-10-27. Equation of State of an Interacting Pion Gas with Realistic $π$--$π$ Interactions. https://doi.org/10.1103/physrevc.53.3057

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