AI 中文总结
本研究针对含标量四重组与类矢量费米子三重组的BNT中微子质量模型，分析其热轻子生成的可行性，发现近简并费米子谱下CP不对称共振可将轻子生成所需标度降至TeV量级，兼顾对撞机可检验性。
AI 中文摘要
我们研究了Babu-Nandi-Tavartkiladze（BNT）模型中的中微子质量与热轻子生成，该模型包含一个标量四重组（$Φ$）和一对类矢量费米子三重组（$Σ$）。在此框架下，中微子质量在树图阶通过有效7维算符$LLHH(H^{\u2020}H)/Λ^3$产生，在单圈阶通过5维算符$LLHH/Λ$产生。即使新物理标度$Λ$为$\rm TeV$量级，该模型也能自然得到亚eV量级的中微子质量，因此成为实验搜索的重要目标。我们探究了该模型中热轻子生成的可行性，由于类矢量费米子的存在，这一过程与经典的基于跷跷板机制的轻子生成不同。研究发现，对于费米子三重组的层级质量谱，当$M_Σ\rgtrsim 10^{7}$ GeV时，轻子生成是可行的。而在近简并情形下，$CP$不对称的共振增强可将该标度降至$\rm TeV$量级，从而使成功的轻子生成与模型最初提出的TeV尺度唯象学、以及对撞机上的可检验性相协调。
英文摘要
We investigate neutrino mass and thermal leptogenesis in the Babu-Nandi-Tavartkiladze (BNT) model featuring a scalar quadruplet ($Φ$) and a pair of vector-like fermion triplets ($Σ$). In this framework, neutrino masses are generated via an effective dimension-7 operator $LLHH(H^{\dagger}H)/Λ^3$ at the tree level and via the dimension-5 operator $LLHH/Λ$ at the one-loop level. It naturally accommodates sub-eV neutrino masses even if the new physics scale $Λ$ is $\mathcal{O}(\rm TeV)$, thus making the model a compelling target for experimental searches. We explore the viability of thermal leptogenesis in this model, which is distinct from the canonical seesaw-based leptogenesis due to the presence of vector-like fermions. We find that leptogenesis is viable for $M_Σ\gtrsim 10^{7}$ GeV for a hierarchical spectrum of fermion triplets. However, in the quasi-degenerate regime, resonant enhancement of the $CP$ asymmetry lowers this scale down to $\mathcal{O}({\rm TeV})$, reconciling successful leptogenesis with the originally motivated TeV-scale phenomenology and testability of the model at colliders.
Comments16 pages, 7 captioned figures, 2 tables
