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Boltzmann Collision Term

Steffen Weinstock
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Abstract

We derive the Boltzmann equation for scalar fields using the Schwinger-Keldysh formalism. The focus lies on the derivation of the collision term. We show that the relevant self-energy diagrams have a factorization property. The collision term assumes the Boltzmann-like form of scattering probability times statistical factors for those self-energy diagrams which correspond to tree level scattering processes. Our proof covers scattering processes with any number of external particles, which come from self-energy diagrams with any number of loops.

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Steffen Weinstock. 2005-10-31. Boltzmann Collision Term. https://doi.org/10.1103/physrevd.73.025005

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