Eur. Phys. J. C 20, 695-711 (2001)
DOI: 10.1007/s100520100655

Bubble walls, CP-violation and electroweak baryogenesis in the MSSM

S.J. Huber¹, P. John² and M.G. Schmidt<sup>3

1</sup>  Bartol Research Institute, 217 Sharp Lab, Newark, DE 19716, USA
²  Instituto de Estructura de la Materia (CSIC), Serrano 123, 28006 Madrid, Spain
³  Institut für Theoretische Physik, Philosophenweg 16, 69120 Heidelberg, Germany

shuber@bartol.udel.edu
john@makoki.iem.csic.es
m.g.schmidt@thphys.uni-heidelberg.de

(Received: 5 February 2001 / Published online: 8 June 2001 -© Springer-Verlag / Società Italiana di Fisica 2001 )

Abstract
We discuss the generation of the baryon asymmetry by a strong first order electroweak phase transition in the early universe, particularly in the context of the MSSM. This requires a thorough numerical treatment of the bubble wall profile in the case of two Higgs fields. CP-violating complex particle masses varying with the Higgs field in the wall are essential. Since in the MSSM there is no indication of spontaneous CP-violation around the critical temperature (contrary to the NMSSM) we have to rely on standard explicit CP-violation. Using the WKB appro xi mation for particles in the plasma we are led to Boltzmann transport equations for the difference of left-handed particles and their CP-conjugates. This asymmetry is finally transformed into a baryon asymmetry by out of equilibrium sphaleron transitions in the symmetric phase. We solve the transport equations and find a baryon asymmetry depending mostly on the CP-violating phases and the wall velocity.

© Società Italiana di Fisica, Springer-Verlag 2001