The Dawn of Quantum Leptogenesis

by Marco Drewes (EPFL)

Monday 15 Mar 2010, 14:00 → 15:00 Europe/Zurich

Salle 727 BSP (EPFL)

Thermal leptogenesis explains the observed matter-antimatter asymmetry of the universe in terms of neutrino masses, consistent with neutrino oscillation experiments. Almost all leptogenesis computations are based on Boltzmann equations. As classical Markovian equations for phase space distribution functions, these suffer from basic conceptual problems when quantum effects like coherent oscillations or memory effects are relevant. Hence, it is important to understand the range of validity of the Boltzmann equations and estimate the size of the corrections. We present a full quantum mechanical calculation of the generated lepton asymmetry based on Kadanoff-Baym equations. Origin of the asymmetry is the departure of the statistical propagator of the heavy Majorana neutrino from the equilibrium propagator, together with CP violating couplings. The lepton asymmetry is calculated directly in terms of Green's functions without referring to `number densities'. A detailed comparis! on with Boltzmann equations shows that conventional leptogenesis calculations have an uncertainty of at least one order of magnitude. Particularly important is the inclusion of thermal damping rates in the full quantum mechanical computation.