论文标题
罕见的顶级Quark衰减$ t \ to cg（g）$在对齐的两吉格斯 - doublet模型中
Rare top-quark decays $t \to cg(g)$ in the aligned two-Higgs-doublet model
论文作者
论文摘要
我们更新了稀有顶级衰减的分支比率的标准模型（SM）预测$ t \ t \ t \ t \ cg（g）$，并评估与$ \ \ nigcal {z} _2 _2 _2 _2 _2 _2 _2 _2 _2 _2 _2 _2 _2 _2 _2 _2 _2 _2 _2 _2 _2 $ symeties可以在对齐中以及四个传统的两higgs-doublet型号（2hdms）中达到的最大速率。考虑到由于获得$ 95.5 \％$置信度的全球拟合所产生的模型参数的相关约束，我们发现$ t \ cg $和$ t \ to cgg $衰减的分支比率可以达到$ 3.36 \ $ 3.36 \ $ 3.36 \ times 10^{ - 9}} $ 2.95 \ time 10^$ 10^$ an 2HDM（A2HDM）。这显然与SM案例不同，在这种情况下，三体衰减$ t \ t \ cgg $的预测分支比率大约比两体衰减$ t \ to cg $大约两个数量级。另一方面，与SM预测相比，在这两个衰减的分支比率的四个常规2HDM中未观察到显着的增强能力。尽管如此，在A2HDM中的$ t \与CG $的预测分支比率仍然超出了未来高劳斯度大型强调撞机的预期敏感性和HADRON-HADRON模式下未来的圆形碰撞器。
We update the Standard Model (SM) predictions for the branching ratios of the rare top-quark decays $t \to cg(g)$, and evaluate the maximum rates that can be reached in the aligned as well as in the four conventional two-Higgs-doublet models (2HDMs) with $\mathcal{Z}_2$ symmetries. Taking into account the relevant constraints on the model parameters resulting from a global fit obtained at the $95.5\%$ confidence level, we find that the branching ratios of $t \to cg$ and $t \to cgg$ decays can reach up to $3.36\times 10^{-9}$ and $2.95\times 10^{-9}$ respectively, being therefore of the same order, in the aligned 2HDM (A2HDM). This is obviously different from the SM case, where the predicted branching ratio of the three-body decay $t \to cgg$ is about two orders of magnitude larger than that of the two-body decay $t \to cg$. On the other hand, compared with the SM predictions, no significant enhancements are observed in the four conventional 2HDMs with $\mathcal{Z}_2$ symmetries for the branching ratios of these two decays. Nevertheless, the predicted branching ratios of $t \to cg$ and $t \to cgg$ decays in the A2HDM are still out of the expected sensitivities of the future high-luminosity Large Hadron Collider and the Future Circular Collider in hadron-hadron mode.
