Supersymmetric CP-violating currents and electroweak baryogenesis

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 t R become proportional to the difference H 2 ∂ µ H 1 − H 1 ∂ µ H 2 (suppressed by ∆β), the Higgsino currents, j µ H i , present contributions proportional to both H 2 ∂ µ H 1 ± H 1 ∂ µ H 2 . For large values of the charged Higgs mass and moderate values of tan β the contribution to the source proportional to H 2 ∂ µ H 1 + H 1 ∂ µ H 2 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 < ∼ v ω < ∼ 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 < ∼ | sin ϕ CP | < ∼ 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:

Resonant flavor oscillations in electroweak baryogenesis

“…Fig. 5 demonstrates in a consistent framework of flavor mixing the resonant baryogenesis regime previously discussed in the context of perturbative mass-insertions [18,19,23,24] or perturbative insertions of mass gradients [20][21][22], and places the origin of this resonance on a firmer theoretical footing.…”

“…Similar resonances were discussed previously in Refs. [18][19][20][21][22][23][24], but our present work establishes its true origin on more theoretically sound footing. The width and height of this resonance are controlled by the ratio L osc /L w for typical thermal modes.…”

“…Eqs. (19) and (20) then describe the quantum evolution of the Wigner functions G(k, x). However, Eqs.…”

“…However, Eqs. (19) and (20) are formidable to solve in practice. Therefore, we simplify them by working to leading non-trivial order in : O( ) in the kinetic equation and O( 0 ) in the constraint equation.…”

“…Our work demonstrated -for the first time in a consistent framework -the resonant baryogenesis regime discussed in Refs. [18][19][20][21][22][23][24] and placed it on a more rigorous theoretical footing. Importantly, we showed that the resonance occurs when the flavor oscillation period is comparable to the variation scale of the background Higgs field.…”