论文标题
在LHC上寻找具有新签名的顶级合作伙伴
Hunting for top partner with a new signature at the LHC
论文作者
论文摘要
类似矢量的顶级合作伙伴在许多新的物理模型中扮演着核心角色，这些模型试图解决层次结构问题。通常认为顶级伴侣会腐烂到夸克和SM玻色子。但是，顶级合作伙伴也可能会衰减到非SM标量和顶级夸克。这种异国情调的衰减频道可以是顶级合作伙伴的主要衰减频道，因此提供了新的窗口来在LHC搜索顶级合作伙伴。在本文中，通过经典的机器学习方法增强了决策树（BDT），我们对LHC上这种新签名的发现潜力进行了模型独立研究。为了抑制主要的QCD背景，我们考虑了亚域但干净的衰减通道$ a \至γγ$。为了完整，考虑到顶级合作伙伴的单个生产过程和配对生产过程。我们发现，对于单个和配对的生产，即使$ br（a \toγγ）$的小（a \toγγ）$，即使是$ \ nmatcal {o} $（0.1 \％），也可以将未来的高光度LHC排除在$ t \ t a $（$ a \toγγ$）上的顶级合作伙伴质量到TEV量表。此外，我们的结果表明，只要顶级合作伙伴比$ 800 \ sim 900 $ GEV，单个生产可以超过14 TEV LHC的生产。
Vector-like top partner plays a central role in many new physics models which attempt to address the hierarchy problem. The top partner is conventionally assumed to decay to a quark and a SM boson. However, it is also possible that the top partner decays to a non-SM scalar and a top quark. Such an exotic decay channel can be the main decay channel of top partner, and thus provides new windows to search for top partner at the LHC. In this paper, with classical machine learning method Boosted Decision Tree (BDT), we perform a model independent study of the discovery potential of this new signature at the LHC. In order to suppress the main QCD background, we consider subdominant but clean decay channel $a\to γγ$. For completeness, the single production process and pair production process of top partner are all taken into account. We find that, for both single and pair production, the future High-Luminosity LHC can exclude the top partner mass up to TeV scale through channel $T\to t a$ ($a\to γγ$), even if $BR(a\to γγ)$ is as small as $\mathcal{O}$(0.1\%). Besides, our result shows that single production can overmatch pair production at 14 TeV LHC, provided that top partner is heavier than $800\sim 900$ GeV.
