Controlled derivation of semiclassical transport equations for electroweak baryogenesis

In this work we study a basic ingredient for the description of baryogenesis at the electroweak phase transition: we provide a controlled derivation of semiclassical transport equations for CP-violating flows for a system of scalar and fermionic fields in the presence of a slowly varying background field. This is the situation in a first order electroweak phase transition, where the background is given by the vacuum expectation value of the Higgs field that varies inside the phase transition front. Starting from the exact equations of motion for the Wigner functions in the Schwinger-Keldysh formalism we perform a systematic expansion in orders of gradients of the background field, including the collision term. This expansion is equivalent to an expansion in powers of the Planck constant $hbar$, and by keeping all terms up to first order in $hbar$ we obtain semiclassical transport equations that are adequate for the description of CP-violation. We find that for both scalar and fermionic fields the equations have a spectral solution which allow for an on-shell description of the plasma excitations. The transport equation for the scalar particles turns out to be a usual classical Boltzmann equation. In the fermionic equations we find quantum corrections that give rise to sources for baryogenesis.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Universität Heidelberg

Year

2002

Author dc:creator

• Weinstock, Steffen M.

Contributors dc:contributor

• Schmidt, Michael G.

Repository record source_url

http://www.ub.uni-heidelberg.de/archiv/2523

OAI identifier oai:identifier

oai:archiv.ub.uni-heidelberg.de:2523