发表机构
Liaoning Normal University（辽宁师范大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出利用味对称模型中固有的 flavons 场克服精确简并中微子质量矩阵导致的轻子生成失效问题，通过引入额外衰变通道产生 CP 不对称性，为基于味对称性的跷跷板模型提供新的轻子生成机制。
AI 中文摘要
虽然 I 型跷跷板模型为同时解释中微子质量的起源和宇宙的重子不对称性提供了一个有吸引力的框架，但味对称性为理解观测到的中微子混合模式提供了一种自然的方法。然而，味对称性所预测的高度受限的中微子质量结构也可能阻碍传统轻子生成的进行。特别是，当 Dirac 中微子质量矩阵 $M^{}_{\rm D}$ 或 Majorana 右手中微子（RHN）质量矩阵 $M^{}_{\rm R}$ 精确简并（即它们与单位矩阵 $I$ 成正比）时，RHN 衰变的 CP 不对称性将消失，这要么是由于不同中微子 Yukawa 耦合列的正交性，要么是由于 RHN 质量的精确简并性。在这项工作中，我们提出 flavons 场（在味对称性中微子质量模型中固有存在，负责生成非平凡的中微子味结构）可以自然地克服这些障碍。对于 $M^{}_{\rm D} \propto I$ 的情况，flavon–RHN 相互作用诱导额外的衰变通道 $N_I \to N_J \phi$，并为 RHN 衰变产生新的 CP 破坏贡献。对于 $M^{}_{\rm R} \propto I$ 的情况，由重矢量样费米子介导的三体衰变 $N_I\rightarrow L^{}_\alpha H\phi$ 即使在 RHN 质量精确简并时也提供了 CP 不对称性来源。我们的结果表明，flavon 扇区提供了中微子味结构与轻子生成之间的自然联系，为基于味对称性的中微子质量模型中的轻子生成提供了一种新机制。
英文摘要
While the type-I seesaw model provides an attractive framework for simultaneously explaining the origin of neutrino masses and the baryon asymmetry of the Universe, flavor symmetries offer a natural approach to understanding the observed neutrino mixing pattern. However, the highly constrained neutrino mass structures predicted by flavor symmetries may also prevent conventional leptogenesis to work. In particular, when the Dirac neutrino mass matrix $M^{}_{\rm D}$ or the Majorana right-handed-neutrino (RHN) mass matrix $M^{}_{\rm R}$ is exactly degenerate (namely, they are proportional to the identity matrix $I$), the CP asymmetry of RHN decays will vanish either due to the orthogonality of different neutrino Yukawa coupling columns or the exact degeneracy of RHN masses. In this work, we propose that the flavon fields (which are inherently present in flavor-symmetry neutrino mass models to be responsible for generating the nontrivial neutrino flavor structure) can naturally overcome these obstacles. For the case of $M^{}_{\rm D} \propto I$, flavon--RHN interactions induce additional decay channels $N_I \to N_J ϕ$ and generate new CP-violating contributions to RHN decays. For the case of $M^{}_{\rm R} \propto I$, three-body decays $N_I\rightarrow L^{}_αHϕ$ mediated by heavy vectorlike fermions provide a CP asymmetry source even when the RHN masses are exactly degenerate. Our results demonstrate that the flavon sector provides a natural connection between neutrino flavor structure and leptogenesis, offering a new mechanism for leptogenesis in flavor-symmetry-based neutrino mass models.
Comments22 pages, 5 figures
