发表机构
Korea Institute for Advanced Study; Institute for Basic Science (IBS); Tsung-Dao Lee Institute & School of Physics and Astronomy, Shanghai Jiao Tong University（韩国高等科学研究院; 基础科学研究院; 上海交大李政道研究所与物理与天文学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文在II型跷跷板模型中提出自发轻子生成的最小实现，通过玻尔兹曼方程分析冻结与冻结进入机制，证明不对称性依赖分支比且与质量无关，为热轻子生成提供无需额外标量或CP破坏的稳健替代方案。
AI 中文摘要
我们研究了II型跷跷板模型中自发轻子生成的最小实现，其中轻子和希格斯不对称性通过衰变和逆衰变过程产生，这些过程驱动等离子体趋向由旋转马约龙背景所决定的位移平衡。我们推导了控制不对称粒子密度演化的完整玻尔兹曼方程组，并通过解析和数值方法确定了冻结和冻结进入机制。由此产生的不对称性主要取决于三重态分支比，且几乎与三重态质量无关。当衰变到轻子或希格斯场的任一模式被抑制时，不对称性随较小分支比的平方根缩放，这反映了对称性结构；一旦任一耦合被关闭，轻子数守恒。我们还表明，在无质量末态极限下，马约龙背景不会诱导标量三重态的CP不对称衰变，因此其影响可忽略不计。我们的结果确立了自发轻子生成作为热II型轻子生成的一种简单而稳健的替代方案，它既不需要额外的标量三重态，也不需要显式的CP破坏相互作用。
英文摘要
We investigate a minimal realization of spontaneous leptogenesis in the type-II seesaw model, where the lepton and Higgs asymmetries are generated as decay and inverse-decay processes drive the plasma toward the displaced equilibrium dictated by a rotating Majoron background. We derive the complete set of Boltzmann equations governing the evolution of asymmetric particle densities and analytically and numerically identify the freeze-out and freeze-in regimes. The resulting asymmetries depend primarily on the triplet branching fractions and are nearly independent of the triplet mass. The asymmetry scales as the square root of the smaller branching fraction when either decay mode into leptons or Higgs fields is suppressed, reflecting the symmetry structure; the lepton number is conserved once either coupling is turned off. We also show that the Majoron background does not induce CP-asymmetric decay of the scalar triplet in the massless final state limit, and thus its impact is negligible. Our results establish spontaneous leptogenesis as a simple and robust alternative to thermal type-II leptogenesis that requires neither additional scalar triplets nor explicit CP-violating interactions.
Comments12 pages, 3 figures
