arXiv 1507.040062015-07hep-ph

通过LHC的混合衰变发现Sbottom

Sbottom discovery via mixed decays at the LHC

Tao Han, Shufang Su, Yongcheng Wu, Bin Zhang, Huanian Zhang

备注：: 26 pages and 7 figures
发表信息：: Phys. Rev. D 92, 115009 (2015)
DOI：: 10.1103/PhysRevD.92.115009

摘要：

在大型强子对撞机的超对称性中寻找底夸克（sbottom）时，通常的做法是假设给定搜索通道的$100\%$衰变分支分数。在现实的MSSM场景中，通常会出现一个以上的重要衰变模式，这大大削弱了LHC当前的sbottom搜索限制。另一方面，多种衰减模式的组合为sbottom搜索提供了替代的发现渠道。在本文中，我们提出了在几个代表性的质量参数的情况下的sbottom衰变。然后我们分析了QCD中的sbottom信号，其中一个sbottom通过$\tilde{b}\rightarrow b χ_1^0,\ b χ_2^0$衰减，另一个通过$\tilde{b} \rightarrow t χ_1^\pm$衰减。随着Gaugino随后衰变为规范玻色子或Higgs玻色子$χ_2^0 \rightarrow Z χ_1^0,\ h χ_1^0$和$χ_1^\pm \rightarrow W^\pm χ_1^0$，我们研究了这些信号在14 TeV的LHC与300 ${\rm fb^{-1}}$积分光度的范围。对于左手底夸克，我们发现，对于250 GeV $< m_{χ_1^0} <$ 350 GeV，在5个$σ$显著性水平上可以发现高达920 GeV的质量，对于$h$通道，在95%置信水平上可以排除高达1050 GeV的质量（$μ>0$）;同样，在95%置信水平下，对于$Z$通道（$μ<0$），它可以在高达840 GeV的能量下被发现，或者在高达900 GeV的能量下被排除。在相同的超对称参数的情况下的sbottom和停止信号相结合，以获得最佳的灵敏度，这是约150 GeV优于个人达到的sbottom或停止。对于一个具有$\tilde{b} \tilde{b}^* \rightarrow b χ_1^0,\ t χ_1^\pm$通道的右下夸克，我们发现在5个$σ$显著性下，可以发现880 GeV的sbottom质量，在95%置信水平下，可以排除1060 GeV的sbottom质量.

英文摘要：

In the search for bottom squark (sbottom) in SUSY at the LHC, the common practice has been to assume a $100\%$ decay branching fraction for a given search channel. In realistic MSSM scenarios, there are often more than one significant decay modes to be present, which significantly weaken the current sbottom search limits at the LHC. On the other hand, the combination of the multiple decay modes offers alternative discovery channels for sbottom searches. In this paper, we present the sbottom decays in a few representative mass parameter scenarios. We then analyze the sbottom signal for the pair production in QCD with one sbottom decaying via $\tilde{b}\rightarrow b χ_1^0,\ b χ_2^0$, and the other one decaying via $\tilde{b} \rightarrow t χ_1^\pm$. With the gaugino subsequent decaying to gauge bosons or a Higgs boson $χ_2^0 \rightarrow Z χ_1^0,\ h χ_1^0$ and $χ_1^\pm \rightarrow W^\pm χ_1^0$, we study the reach of those signals at the 14 TeV LHC with 300 ${\rm fb^{-1}}$ integrated luminosity. For a left-handed bottom squark, we find that a mass up to 920 GeV can be discovered at 5$σ$ significance for 250 GeV $< m_{χ_1^0} <$ 350 GeV, or excluded up to 1050 GeV at the 95\% confidence level for the $h$ channel ($μ>0$); similarly, it can be discovered up to 840 GeV, or excluded up to 900 GeV at the 95\% confidence level for the $Z$ channel ($μ<0$). The sbottom and stop signals in the same SUSY parameter scenario are combined to obtain the optimal sensitivity, which is about 150 GeV better than the individual reach of the sbottom or stop. For a right-handed bottom squark with $\tilde{b} \tilde{b}^* \rightarrow b χ_1^0,\ t χ_1^\pm$ channel, we find that the sbottom mass up to 880 GeV can be discovered at 5$σ$ significance, or excluded up to 1060 GeV at the 95\% confidence level.

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