Improved Results in Supersymmetric Electroweak Baryogenesis
M. Carena, M. Quiros, M. Seco, C. E. M. Wagner
TL;DR
The paper re-derives diffusion equations for electroweak baryogenesis in the MSSM with a light stop and provides a consistent definition of CP-violating sources in terms of derivatives of CP-violating currents. It demonstrates that the leading source term proportional to $\epsilon_{ij} H_i \partial^{\mu} H_j$ is not suppressed, contrasting with some prior claims, and uses a Green-function / Wigner-space approach to compute the chargino-sector currents and the resulting sources. Solving the diffusion equations, the authors show parameter regions where the observed baryon asymmetry $\eta$ is achievable without violating experimental constraints, thereby reinforcing the viability of MSSM electroweak baryogenesis. Overall, the work clarifies the structure of CP-violating sources, reconciles discrepancies in the literature, and highlights resonant enhancements around $M_2 \approx |\mu|$ as well as the role of the Higgs sector parameters ($m_A$, $\tan\beta$).
Abstract
Electroweak baryogenesis provides a very attractive scenario to explain the origin of the baryon asymmetry. The mechanism of electroweak baryogenesis makes use of the baryon number anomaly and relies on physics that can be tested experimentally. It is today understood that, if the Higgs mass is not larger than 120 GeV, this mechanism may be effective within supersymmetric extensions of the Standard Model. In this work, we reconsider the question of baryon number generation at the electroweak phase transition within the context of the minimal supersymmetric extension of the Standard Model. We derive the relevant diffusion equations, give a consistent definition of the sources, and compare our results with those appearing in the recent literature on this subject