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arXiv · hep-ph/0212355

Exact Calculation of Ring Diagrams and the Off-shell Effect on the Equation of State

Jinfeng Liao·Xianglei Zhu·Pengfei Zhuang
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Abstract

The partition function with ring diagrams at finite temperature is exactly caluclated by using contour integrals in the complex energy plane. It contains a pole part with temperature and momentum dependent mass and a phase shift part induced by off-shell effect in hot medium. The thermodynamic potentials for $ϕ^4$ and $ϕ^3$ interactions are calculated and compared with the quasi-particle (pole) approximation. It is found that the off-shell effect on the equation of state is remarkable.

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Jinfeng Liao, Xianglei Zhu, Pengfei Zhuang. 2003-05-18. Exact Calculation of Ring Diagrams and the Off-shell Effect on the Equation of State. https://doi.org/10.1103/physrevd.67.105023

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