Speaker
Description
When studying particle density evolution, within the classical Boltzmann approach, we must include all number-changing processes in which the particle participates, typically decays or scatterings. At higher orders, other types of reactions may become relevant as well. We formulate a diagrammatic unitarity-based algorithm to complete the set of contributing reactions. Initially, the particles are treated as classical point-like objects whose interactions are described through zero-temperature quantum field theory. In equilibrium, their phase space densities are the Maxwell-Boltzmann exponentials. Surprisingly, the algorithm automatically accounts for the effects of thermal corrections. The framework will be demonstrated through CP asymmetry calculations and higher-order corrections to particle decays in a thermal medium.
