Yukawa Interactions and Supersymmetric Electroweak Baryogenesis

We analyze the quantum transport equations for supersymmetric electroweak baryogenesis including previously neglected bottom and tau Yukawa interactions and show that they imply the presence of a previously unrecognized dependence of the cosmic baryon asymmetry on the spectrum of third generation quark and lepton superpartners. For fixed values of the $CP$-violating phases in the supersymmetric theory, the baryon asymmetry can vary in both magnitude and sign as a result of the squark and slepton mass dependence. For light, right-handed top and bottom quark superpartners, the baryon number creation can be driven primarily by interactions involving third generation leptons and their superpartners.

Figure 1

Baryon asymmetry in units of the observed value as a function of RH bottom squark mass. The two solid (dashed) curves were obtained using the full numerical (large $\tan \beta$ analytic) solution. Light (dark) curves correspond to RH stau mass of 90 GeV (1 TeV). The dotted curve gives results neglecting bottom and tau Yukawa interactions.