发表机构
International Centre for Theoretical Physics Asia-Pacific; KEK Theory Center; University of Münster; Kavli IPMU (WPI), UTIAS, The University of Tokyo（亚太理论物理中心; 高能加速器研究机构理论中心; 明斯特大学; 东京大学汤川秀树物理学与宇宙学研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文推导了电弱交叉过程中重子数演化的玻尔兹曼方程，精确计算了冻结丰度，给出了两个弱子转换因子，揭示了温度变化对重子数冻结的影响。
AI 中文摘要
弱子（sphaleron）跃迁将早期宇宙标准模型等离子体中的轻子不对称性转化为重子不对称性，同时守恒重子数减轻子数 $B-L$ 及其各味电荷。因此，重子不对称性也可以由具有零 $B-L$ 的味轻子不对称性产生。在对称相和破缺相中的标准平衡计算是在恒定温度下进行的，因此忽略了希格斯期望值和弱子速率都随温度在电弱交叉过程中变化的事实。我们推导了跨越交叉过程的重子数演化的玻尔兹曼方程，并计算了冻结丰度，其中包含了巨正则配分函数和微扰希格斯期望值的高阶修正。这给出了两个弱子转换因子：对于 $B-L$ 为 $C_\text{sph} = 0.3328(5)$，对于由带电轻子汤川耦合加权的味电荷为 $\mathcal{F}_\text{sph} = 0.0279(19)$。
英文摘要
Weak sphaleron transitions turn a lepton asymmetry of the Standard Model plasma in the early Universe into a baryon asymmetry, conserving baryon-minus-lepton number $B-L$ and its individual flavored charges. A baryon asymmetry can thus also arise from flavored lepton asymmetries with vanishing $B-L$. Standard equilibrium calculations in the symmetric and broken phases are performed at constant temperature and hence neglect the fact that both the Higgs expectation value and the sphaleron rate vary as functions of temperature across the electroweak crossover. We derive a Boltzmann equation for the baryon number evolution across the crossover and calculate the freeze-out abundance including higher-order corrections to both the grand canonical partition function and the perturbative Higgs expectation value. This yields two sphaleron conversion factors: $C_\text{sph} = 0.3328(5)$ for $B-L$ and $\mathcal{F}_\text{sph} = 0.0279(19)$ for the flavored charges weighted by the charged-lepton Yukawa couplings.
Comments52 pages, 11 figures, 21 diagrams
