Supersymmetric CP-violating Currents and Electroweak Baryogenesis
M. Carena, J. M. Moreno, M. Quiros, M. Seco, C. E. M. Wagner
TL;DR
The paper develops a first-principles framework for MSSM electroweak baryogenesis by computing CP-violating currents from the stop and chargino/Higgsino sectors in a nontrivial Higgs background using the finite-temperature Keldysh formalism with an all-orders resummation of Higgs mass insertions. It derives both stop- and Higgsino-induced sources, feeds them into diffusion equations, and provides analytic and numerical solutions for the resulting baryon asymmetry, highlighting the significance of Higgsino contributions and the dependence on wall dynamics and thermal rates. The results indicate that viable baryogenesis can be achieved for modest CP-violating phases and specific MSSM parameter choices, with LEP2 Higgs constraints offering important phenomenological guidance. The work emphasizes the interplay between CP violation, wall profiles, and thermal transport in shaping the BAU in the MSSM.
Abstract
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^μ_{\widetilde t_R} become proportional to the difference H_2 \partial^μH_1-H_1 \partial^μ H_2 (suppressed by Δβ), the Higgsino currents, j^μ_{\widetilde{H}_i}, present contributions proportional to both H_2 \partial^μH_1\pm H_1 \partial^μ H_2. For large values of the charged Higgs mass and moderate values of \tanβthe contribution to the source proportional to H_2 \partial^μH_1+H_1 \partial^μ H_2 in the diffusion equations become sizeable, although it is suppressed by the Higgsino number violating interaction rate Γ_μ^{-1/2}. For small values of the wall velocity, 0.04\simlt v_ω\simlt 0.1, the total contribution leads to acceptable values of the baryon asymmetry for values of the CP-violating phases φ_{CP} in the range 0.04\simlt|\sinφ_{CP}|\simlt 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.