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arXiv · 2309.09335

Analytical structure of the binary collision integral and the ultrarelativistic limit of transport coefficients of an ideal gas

David Wagner·Victor E. Ambrus·Etele Molnar
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Abstract

In this paper we discuss the analytical properties of the binary collision integral for a gas of ultrarelativistic particles interacting via a constant cross-section. Starting from a near-equilibrium expansion over a complete basis of irreducible tensors in momentum space we compute the linearized collision matrices analytically. Using these results we then numerically compute all transport-coefficients of relativistic fluid dynamics with various power-counting schemes that are second-order in Knudsen and/or inverse Reynolds numbers. Furthermore, we also exactly compute the leading-order contribution with respect to the particle mass to the coefficient of bulk viscosity, the relaxation time, and other second-order transport coefficients of the bulk viscous pressure.

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David Wagner, Victor E. Ambrus, Etele Molnar. 2023-09-17. Analytical structure of the binary collision integral and the ultrarelativistic limit of transport coefficients of an ideal gas. https://doi.org/10.1103/physrevd.109.056018

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