Nonequilibrium QFT approach to baryogenesis

Who: Matti Herranen (NBI)
When: Monday, February 4, 2013 at 14:15
Where: U49

The observed baryon asymmetry of the Universe may have been produced dynamically in the very early Universe by a baryogenesis process. Leptogenesis and Electroweak baryogenesis (EWBG) are among the most prominent candidates for a successful baryogenesis. For reliable calculations of the asymmetry first principle methods of nonequilibrium quantum field theory are required. We construct a transport theory of baryogenesis based on the Schwinger-Keldysh or Closed Time Path (CTP) formalism of nonequilibrium QFT. The resulting kinetic equations incorporate finite density medium effects and quantum coherence effects and therefore provide a generalization to standard (quantum) Boltzmann equations.

For leptogenesis we find that the finite density corrections from loop integrals typically lead to an enhancement of the asymmetry. In the resonant regime with nearly degenerate right-handed neutrino masses, our results confirm the general structure of the resonant enhancement of CP-violation, however, novel terms related to flavour oscillations can be important in the dynamics. For EWBG we show that quantum coherence effects related to particle-antiparticle (flavour) mixing may have a large effect on the generated asymmetry due to flavour dynamics and quantum reflection from the bubble wall.

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