Speaker
Dr
Alexander Kartavtsev
(Max-Planck-Institute for Physics)
Description
We study runaway and crossing regimes of resonant leptogenesis, which have not been addressed before, using non-equilibrium quantum field theory. In the runaway regime the mass difference monotonously grows with temperature, whereas in the crossing regime the mass difference initially decreases, such that the effective masses become equal at some temperature. We analytically demonstrate that vanishing of the difference of the effective masses by no means implies vanishing or suppression of CP-violation. In the vicinity of the crossing point the asymmetry calculated in the Boltzmann approximation develops a spurious peak, which signals the breakdown of the quasiparticle approximation. In the exact result the spurious enhancement is exactly compensated by coherent transitions between the two mass shells. Despite the breakdown of the quasiparticle approximation the purely off-shell contributions remain small even at the crossing point. The results of this work provide a reference point for various approximations schemes including the density matrix equations.
Author
Dr
Alexander Kartavtsev
(Max-Planck-Institute for Physics)
Co-author
Dr
Andreas Hohenegger
(The University of Stavanger)
