Leptogenesis: CPT & CTP
Prof. Dr. Bj?rn Garbrecht (Inst. f. Theoret. Teilchenphysik u. Kosmologie, RWTH Aachen)

We derive kinetic equations for Leptogenesis in the early Universe from first principles within the Closed Time Path (CTP) framework, a.k.a. the "in-in formalism". It is shown that the somewhat heuristic procedure of subtraction of real intermediate states, that needs to be applied in the conventional in-out approach in order to comply with the CTP theorem, is not necessary within the CPT approach. Besides this issue of rather theoretical interest, the resulting kinetic equations exhibit quantum statistical corrections that are relevant in the parametric regime of weak washout. Our methods may also serve as a starting point for further improvements in the quantitative predictions for Leptogenesis.