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arXiv · 2104.06395

Cutting rules on a cylinder: a bottom-up approach to quantum kinetic theory for the early universe

Tomáš Blažek·Peter Maták
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Abstract

Nonequilibrium quantum field theory is often used to derive an approximation for the evolution of number densities and asymmetries in astroparticle models when a more precise treatment of quantum thermal effects is required. This work presents an alternative framework using the zero-temperature quantum field theory, $S$-matrix unitarity, and classical Boltzmann equation as starting points leading to a set of rules for calculations of thermal corrections to reaction rates. Statistical factors due to on-shell intermediate states are obtained from the cuts of forward diagrams with multiple spectator lines. It turns out that it is equivalent to cutting closed diagrams on a cylindrical surface.

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Tomáš Blažek, Peter Maták. 2021-08-18. Cutting rules on a cylinder: a bottom-up approach to quantum kinetic theory for the early universe. https://doi.org/10.1140/epjc%2Fs10052-021-09874-3

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