"Table 51" of "Search for top squark pair production in final states with one isolated lepton, jets, and missing transverse momentum in $\sqrt{s}=$ 8 TeV pp collisions with the ATLAS detector"

CERN-LHC. The results of a search for top squark (stop) pair production in final states with one isolated lepton, jets, and missing transverse momentum are reported. The analysis is performed with proton-proton collision data at $\sqrt{s}=$ 8 TeV collected with the ATLAS detector at the LHC in 2012 corresponding to an integrated luminosity of 20 fb$^{-1}$. The lightest supersymmetric particle (LSP) is taken to be the lightest neutralino which only interacts weakly and is assumed to be stable. The stop decay scenarios considered are those to a top quark and the LSP as well as to a bottom quark and the lightest chargino, where the chargino decays to the LSP by emitting a W boson. A wide range of scenarios with different mass splittings between the stop, the lightest neutralino and the lightest chargino are considered, including cases where the W bosons or the top quarks are off-shell. Decay scenarios involving the heavier charginos and neutralinos are addressed using a set of phenomenological models of supersymmetry. No significant excess over the Standard Model prediction is observed. A stop with a mass between 210 and 640 GeV decaying directly to a top quark and a massless LSP is excluded at 95% confidence level, and in models where the mass of the lightest chargino is twice that of the LSP, stops are excluded at 95% confidence level up to a mass of 500 GeV for an LSP mass in the range of 100 to 150 GeV. Stringent exclusion limits are also derived for all other considered stop decay scenarios, and generic upper limits are set on the visible cross-section for processes beyond the Standard Model.

欧洲核子研究中心大型强子对撞机（CERN-LHC）相关实验：本研究报告了在包含单个孤立轻子、喷注与缺失横向动量的末态中，搜寻顶超对称夸克（top squark，stop）成对产生的实验结果。本分析使用大型强子对撞机的ATLAS探测器于2012年采集的质心系能量√s=8 TeV的质子-质子碰撞数据，对应的积分亮度为20 fb⁻¹。本研究设定最轻超对称粒子（LSP，lightest supersymmetric particle）为仅通过弱相互作用发生耦合且稳定存在的最轻中性微子。所考量的顶超对称夸克衰变模式包括：衰变至顶夸克与LSP，以及衰变至底夸克与最轻 chargino（chargino）；其中最轻 chargino将通过发射W玻色子的方式衰变至LSP。本分析覆盖了顶超对称夸克、最轻中性微子与最轻 chargino间存在不同质量劈裂的大量场景，包括W玻色子或顶夸克处于离壳态的情形。针对涉及更重 chargino与中性微子的衰变模式，本分析采用了一系列超对称现象学模型进行处理。未观测到超出标准模型预言的显著信号超出。对于质量介于210 GeV至640 GeV之间、直接衰变至顶夸克与无质量LSP的顶超对称夸克，我们以95%置信水平将其排除；在最轻 chargino质量为LSP两倍的模型中，当LSP质量处于100 GeV至150 GeV区间时，质量至多为500 GeV的顶超对称夸克均以95%置信水平被排除。本研究还为所有其他考量的顶超对称夸克衰变模式设定了严格的排除极限，并为超出标准模型的过程的可见截面设定了一般性上限。