Supergauge interactions and electroweak baryogenesis
We present a complete treatment of the diffusion processes for supersymmetric electroweak baryogenesis that characterizes transport dynamics ahead of the phase transition bubble wall within the symmetric phase. In particular, we generalize existing approaches to distinguish between chemical potentials of particles and their superpartners. This allows us to test the assumption of superequilibrium (equal chemical potentials for particles and sparticles) that has usually been made in earlier studies. We show that in the Minimal Supersymmetric Standard Model, superequilibrium is generically maintained — even in the absence of fast supergauge interactions — due to the presence of Yukawa interactions. We provide both analytic arguments as well as illustrative numerical examples. We also extend the latter to regions where analytical approximations are not available since down-type Yukawa couplings or supergauge interactions only incompletely equilibrate. We further comment on cases of broken superequilibrium wherein a heavy superpartner decouples from the electroweak plasma, causing a kinematic bottleneck in the chain of equilibrating reactions. Such situations may be relevant for baryogenesis within extensions of the MSSM. We also provide a compendium of inputs required to characterize the symmetric phase transport dynamics.
Additional Information© SISSA 2009. Received 21 September 2009, accepted for publication 22 October 2009. Published 23 December 2009. This work was supported in part by Department of Energy contracts DE-FG02-08ER41531 and DE-FG02-95ER40896, and the Wisconsin Alumni Research Foundation. MJRM thanks NORDITA, the Apsen Center for Physics, and TRIUMF, where part of this work was completed.
Submitted - 0908.2187