Supersymmetric CP-violating Currents and Electroweak Baryogenesis

In this work we compute the CP-violating currents of the right-handed stops and Higgsinos, induced by the presence of non-trivial vacuum expectation values of the Higgs fields within the context of the minimal supersymmetric extension of the Standard Model (MSSM) with explicit CP-violating phases. Using the Keldysh formalism, we perform the computation of the currents at finite temperature, in an expansion of derivatives of the Higgs fields. Contrary to previous works, we implement a resummation of the Higgs mass insertion effects to all orders in perturbation theory. While the components of the right-handed stop current j t̃R become proportional to the difference H2∂ H1−H1∂H2 (suppressed by ∆β), the Higgsino currents, j H̃i , present contributions proportional to both H2∂ H1 ±H1∂H2. For large values of the charged Higgs mass and moderate values of tan β the contribution to the source proportional to H2∂ H1 +H1∂ H2 in the diffusion equations become sizeable, although it is suppressed by the Higgsino number violating interaction rate Γ −1/2 μ . For small values of the wall velocity, 0.04 < ∼ vω < ∼ 0.1, the total contribution leads to acceptable values of the baryon asymmetry for values of the CP-violating phases φCP in the range 0.04 < ∼ | sinφCP | < ∼ 1. Finally, we comment on the relevance of the latest results of Higgs searches at LEP2 for the mechanism of electroweak baryogenesis within the MSSM. Present address: Department of Physics, University of Virginia, 382 McCormick Road, P.O. Box 400714, Charlottesville, VA 22904-4714.