论文标题
矢量leptoquark-scalar盒图在pati-salam统一与矢量般的家族的重要性
Importance of vector leptoquark-scalar box diagrams in Pati-Salam unification with vector-like families
论文作者
论文摘要
我们研究了涉及涉及载体leptoquark（LQ）和标量域的盒子图引起的中膜衰变的Lepton风味，该杂物与矢量样家族的Pati-Salam（PS）统一。向量LQ对应于与PS量规对称性断裂相关的巨大仪表，标量场是PS断裂场的物理自由度。 LQ通常会导致违反快速风味的衰减，例如$ k_l \ toμe$，除非其质量尺度高于PEV量表。引入了类似矢量的家族来抑制LQ介导的树级贡献，并解释了现实的费米昂质量矩阵。在本文中，我们指出，即使抑制了树级的贡献，也不可避免地会对那些由一个LQ和一个标量场介导的盒子图介导的介子图贡献一环的贡献。我们考虑了一个用于演示的具体模型，并发现当一环诱导的中膜衰变与实验限制一致时，矢量样的费米质量对于给定的LQ质量具有上限。如果耦合的组合不抑制$ k_l \ toμe$衰减，则类似矢量的费米质量应比3 tev亮3 teV。我们的发现将说明涉及通用模型中对称性破坏标量的LQ和物理模式的框图的重要性。
We study lepton flavor violating meson decays induced by box diagrams involving a vector leptoquark (LQ) and scalar fields in Pati-Salam (PS) unification with vector-like families. The vector LQ corresponds to the massive gauge boson associated with the PS gauge symmetry breaking and the scalar fields are the physical degrees of freedom of the PS breaking field. The LQ generally causes the rapid flavor violating decays, such as $K_L \to μe$, at the tree-level unless its mass scale is higher than PeV scale. The vector-like families are introduced to suppress the tree-level contributions mediated by the LQ and explain the realistic fermion mass matrices. In this paper, we point out that there are inevitable one-loop contributions to those meson decays from the box diagrams mediated by both one LQ and one scalar field, even if the tree-level contributions are suppressed. We consider a concrete model for demonstration, and find that the vector-like fermion masses have an upper bound for a given LQ mass when the one-loop induced meson decays are consistent with the experimental limits. The vector-like fermion mass should be lighter than 3 TeV for 20 TeV LQ, if a combination of the couplings does not suppress $K_L \to μe$ decay. Our findings would illustrate importance of the box diagrams involving both LQ and physical modes of symmetry breaking scalars in generic models.
