AI 中文总结
本文提出无反常可重整化轴向 $U_A(1)_{L_μ-L_τ}$ 模型，研究其在 $A'$ 质量 MeV 至 TeV 范围的实验信号，结合多类实验结果给出 $(m_{A'},g_X)$ 平面唯象约束，未来缪子对撞机可通过角分布分辨其手征性。
AI 中文摘要
我们提出了一种无反常且可重整化的轴向 $U_A(1)_{L_μ-L_τ}$ 模型，并研究其在 $A'$ 质量从 MeV 量级到 TeV 量级下的实验信号。左手与右手带电轻子的相反电荷禁止了常规的缪子和陶子汤川相互作用，它们的质量由单态标量和重矢量样轻子通过通用跷跷板机制产生。我们聚焦于重矢量样轻子、小的轻-重混合以及 $m_s\raisebox{0.5ex}{$\textstyle \buildrel > \belowlimits \raisebox{-0.5ex}{$\textstyle \thicksim$}$}10~\text{GeV}$ 的情况，在该极限下，此处考虑的可观测量主要依赖于 $(m_{A'},g_X)$，而其他模型参数则受混合和微扰性约束。我们将该基准与当前实验搜寻结果对比：对于中微子三生产，我们的有限 $m_μ$ 计算表明，$A'$ 会修改轴向弱系数，而非常规 $L_μ-L_τ$ 模型相关的矢量系数；纵向模式增强缪子轫致辐射，并对 $(g-2)_μ$ 产生负贡献，在我们的基准中后者超过标量贡献。结合这些结果与不可见介子衰变、四缪子共振搜寻，我们在 $(m_{A'},g_X)$ 平面上总结了唯象约束。当 $m_{A'}\raisebox{0.5ex}{$\textstyle \buildrel > \belowlimits \raisebox{-0.5ex}{$\textstyle \thicksim$}$}m_μ$ 时，矢量和轴矢量末态辐射率几乎相同，因此可通过率匹配获得相应对撞机限制。在未来缪子对撞机中，仅总率无法完全分辨相互作用结构，而角分布（尤其是 $\bar{μ}^+μ^-\toτ^+τ^-$ 的前后不对称性）仍保留对手征性的直接敏感性。
英文摘要
We propose an anomaly-free and renormalizable axial $U_A(1)_{L_μ-L_τ}$ model and study its experimental signatures for $A'$ masses from the MeV scale to the TeV scale. The opposite charges of the left- and right-handed charged leptons forbid the usual muon and tau Yukawa interactions. Their masses are instead generated by a singlet scalar and heavy vector-like leptons through a universal-seesaw mechanism. We focus on heavy vector-like leptons, small light--heavy mixing, and $m_s\gtrsim10~\mathrm{GeV}$. In this limit, the observables considered here depend mainly on $(m_{A'},g_X)$, while the other model parameters are restricted by mixing and perturbativity. We confront this benchmark with current experimental searches. For neutrino trident production, our finite-$m_μ$ calculation shows that $A'$ modifies the axial weak coefficient, rather than the vector coefficient relevant to the usual $L_μ-L_τ$ model. The longitudinal mode enhances muon bremsstrahlung and gives a negative contribution to $(g-2)_μ$; the latter dominates over the scalar contribution in our benchmark. Combining these results with invisible meson decays and four-muon resonance searches, we summarize the phenomenological constraints in the $(m_{A'},g_X)$ plane. For $m_{A'}\gg m_μ$, vector and axial final-state-radiation rates become nearly identical, so the corresponding collider limits can be obtained by rate matching. At a future muon collider, the total rate alone does not fully resolve the interaction structure, whereas angular distributions, especially the forward--backward asymmetry in $μ^+μ^-\toτ^+τ^-$, retain direct sensitivity to chirality.
Comments27 pages, 3 figures
