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arXiv 2011.11949hep-phhep-ex
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Di-Higgs产生作为味变化中性Yukawa耦合的探针

Di-Higgs production as a probe of flavor changing neutral Yukawa couplings

Shi-Ping He

摘要:

顶级合作伙伴在许多新的物理模型中表现良好。为了避免量子反常,通常引入矢量类夸克$T_{L,R}$。探测它们与标准模型粒子的相互作用是至关重要的。然而,在当前和未来的实验中,风味改变中性偶联总是难以直接检测。在本文中,我们将展示如何通过间接的di-Higgs生产来约束味道改变中性Yukawa耦合$Tth$。我们考虑包含一对规范单重态$T_{L,R}$的简化模型。在微扰么正性和实验条件的约束下,我们选择了$m_T=400~\mathrm{GeV},s_L=0.2$和$m_T=800~\mathrm{GeV},s_L=0.1$作为基准点。通过对振幅的分析和对数值截面的计算,我们发现由于$(y_{L,R}^{tT})^4$的行为,目前对di-Higgs产生的限制已经超过了幺正性的限制。对于$m_T=400~\mathrm{GeV}$和$s_L=0.2$的情况,$\mathrm{Re}y_{L,R}^{tT}$和$\mathrm{Im}y_{L,R}^{tT}$可以在具有$2σ$ CL的HL-LHC上在范围$(-0.4, 0.4)$内被最佳地限制。对于$m_T=800~\mathrm{GeV}$和$s_L=0.1$的情况,$\mathrm{Re}y_{L,R}^{tT}$和$\mathrm{Im}y_{L,R}^{tT}$可以在具有$2σ$ CL的HL-LHC上在范围$(-0.5, 0.5)$内被最优地限制。反常的三重Higgs耦合$δ_{hhh}$也能影响对$y_{L,R}^{tT}$的约束。最后,我们发现在某些情况下,顶夸克电偶极矩可以在离轴区域给出更强的$y_{L,R}^{tT}$束缚。

英文摘要:

Top partners are well motivated in many new physics models. Usually, vector like quarks $T_{L,R}$ are introduced to avoid the quantum anomaly. It is crucial to probe their interactions with the standard model particles. However, flavor changing neutral couplings are always difficult to detect directly in the current and future experiments. In this paper, we will show how to constrain the flavor changing neutral Yukawa coupling $Tth$ through the di-Higgs production indirectly. We consider the simplified model including a pair of gauge singlet $T_{L,R}$. Under the perturbative unitarity and experimental constraints, we choose $m_T=400~\mathrm{GeV},s_L=0.2$ and $m_T=800~\mathrm{GeV},s_L=0.1$ as benchmark points. After the analysis of amplitude and evaluation of the numerical cross sections, we find that the present constraints from di-Higgs production have already surpassed the unitarity bound because of the $(y_{L,R}^{tT})^4$ behavior. For the case of $m_T=400~\mathrm{GeV}$ and $s_L=0.2$, $\mathrm{Re}y_{L,R}^{tT}$ and $\mathrm{Im}y_{L,R}^{tT}$ can be bounded optimally in the range $(-0.4, 0.4)$ at HL-LHC with $2σ$ CL. For the case of $m_T=800~\mathrm{GeV}$ and $s_L=0.1$, $\mathrm{Re}y_{L,R}^{tT}$ and $\mathrm{Im}y_{L,R}^{tT}$ can be bounded optimally in the range $(-0.5, 0.5)$ at HL-LHC with $2σ$ CL. The anomalous triple Higgs coupling $δ_{hhh}$ can also affect the constraints on $y_{L,R}^{tT}$. Finally, we find that the top quark electric dipole moment can give stronger bounds of $y_{L,R}^{tT}$ in the off-axis regions for some scenarios.

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