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arXiv 2004.12155hep-ph
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希格斯玻色子到$γZ$衰变作为变味中性Yukawa耦合的探针

Higgs boson to $γZ$ decay as a probe of flavour changing neutral Yukawa couplings

Shi-Ping He

摘要:

随着对Higgs粒子研究的深入,Higgs粒子的精确测量可以间接地为新物理的探索服务。在许多新的物理模型中,矢量类夸克$T_L,~T_R$是自然产生的。探测它们与标准模型粒子的耦合是很重要的。在这项工作中,我们考虑的单重$T_L,~T_R$扩展模型,并显示如何约束的$Tth$耦合通过$h\rightarrowγZ$衰变在高亮度LHC。首先,我们简单地导出了当其他耦合为零时$|y_{L,~R}^{tT}|$的微扰么正性界。为了优化的情况下,我们采取$m_T$ = 400 GeV和$s_L$ = 0.2考虑到实验的限制。在这个基准点下,我们发现由于双重增强,$h\rightarrowγZ$衰变的未来界可以将$y_{L,~R}^{tT}$的正向实部限制为O(1)。对于$y_{L,~R}^{tT}$的实部,它总是被微扰么正性所超越。此外,我们还发现在某些情况下,顶夸克电偶极矩比微扰么正性和离轴区域的$h\rightarrowγZ$衰变能给出更强的束缚(特别是$y_{L,~R}^{tT}$的虚部).

英文摘要:

With the deeper study of Higgs particle, Higgs precision measurements can be served to probe new physics indirectly. In many new physics models, vector-like quarks $T_L,~T_R$ occur naturally. It is important to probe their couplings with standard model particles. In this work, we consider the singlet $T_L,~T_R$ extended models and show how to constrain the $Tth$ couplings through the $h\rightarrowγZ$ decay at high-luminosity LHC. Firstly, we derive the perturbative unitarity bounds on $|y_{L,~R}^{tT}|$ with other couplings set to be zeros simply. To optimize the situation, we take $m_T$ = 400 GeV and $s_L$ = 0.2 considering the experimental constraints. Under this benchmark point, we find that the future bounds from $h\rightarrowγZ$ decay can limit the real parts of $y_{L,~R}^{tT}$ in the positive direction to be O(1) because of the double enhancement. For the real parts of $y_{L,~R}^{tT}$ in the negative direction, it is always surpassed by the perturbative unitarity. Moreover, we find that the top quark electric dipole moment can give stronger bounds (especially the imaginary parts of $y_{L,~R}^{tT}$) than the perturbative unitarity and $h\rightarrowγZ$ decay in the off-axis regions for some scenarios.

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