Title: Muon g-2 and rare top decays in up-type specific variant axion models Show Chinese title

Title: μ子 g-2 和上型特异性变体轴子模型中的稀有顶夸克衰变

Abstract: The invisible variant axion models (VAM's) offer a very attractive solution for the strong CP problem without the domain wall problem. We consider the up-type specific variant axion models and examine their compatibility with the muon $g-2$ anomaly and the constraints from lepton flavor universality, several flavor observables, and top quark measurements. We find that the combined $\chi^2$ fit favors the parameters $m_A\sim 15$ GeV and $\tan\beta \sim 40$, the same as the type-X 2HDM. Moreover, we find that there are no conflict with any flavor observables as long as the mixing angle $\rho_u$ is sufficiently small. In particular, a small nonzero mixing angle $\rho_u \sim \pi/100$ is slightly favored by the observed $B_s \to \mu\mu$ branching ratio. The up-specific VAM predicts the flavor-violating top rare decay $t\to uA$ followed by $A \to \tau\tau$, which would provide a smoking gun signature at the LHC. We show that current searches of $A$ already impose some constraints on the parameter space but are not sensitive to the most interesting light $m_A$ region. We propose an efficient search strategy that employs di-tau tagging using jet substructure information, and demonstrate that it can enhance the sensitivity on $BR(t \to uA)$, especially in the light $m_A$ region. This model also predicts the flavor-violating decay of heavy Higgs bosons, such as $H \to t u$, that would suppress the $H \to \tau\tau/\mu\mu$ decays. We also examine the up-specific VAM with the muon-specific lepton sector and the down-type specific VAM's as interesting alternative scenarios. Show Chinese abstract

Abstract: 不可见变体轴子模型（VAM's）为强CP问题提供了一个非常有吸引力的解决方案，而不会产生域墙问题。 我们考虑上型特定的变体轴子模型，并检验它们与缪子$g-2$异常以及轻子味普适性、几个味观测量和顶夸克测量的约束是否兼容。 我们发现，结合的$\chi^2$拟合倾向于参数$m_A\sim 15$GeV 和$\tan\beta \sim 40$，与类型-X 2HDM 相同。 此外，我们发现只要混合角$\rho_u$足够小，就不会与任何味观测量冲突。 特别是，一个微小的非零混合角$\rho_u \sim \pi/100$稍微被观测到的$B_s \to \mu\mu$分支比所支持。 针对特定的VAM预测了风味违反的顶夸克稀有衰变$t\to uA$，随后发生$A \to \tau\tau$，这将在大型强子对撞机上提供一个明确的信号。 我们表明，目前对$A$的搜索已经对参数空间施加了一些限制，但对最有趣的轻量级$m_A$区域不敏感。 我们提出了一种高效的搜索策略，该策略使用喷注结构信息进行双τ标签，并证明它能够增强对$BR(t \to uA)$的敏感性，特别是在轻量级$m_A$区域。 该模型还预测了重希格斯玻色子的味违反衰变，例如$H \to t u$，这会抑制$H \to \tau\tau/\mu\mu$衰变。 我们还研究了针对上夸克的VAM与针对缪子的轻子区以及针对下夸克类型的VAM作为有趣的替代情景。