Cutting rules on a cylinder: a simplified diagrammatic approach to quantum kinetic theory
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AbstractNonequilibrium 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.
1998 ◽
Vol 196
(3)
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pp. 535-570
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2013 ◽
Vol 718
(3)
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pp. 1119-1124
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