"Table 21" of "Search for direct top squark pair production in events with a Z boson, b-jets and missing transverse momentum in sqrt(s)=8 TeV pp collisions with the ATLAS detector"

CERN-LHC. A search is presented for direct top squark pair production using events with at least two leptons including a same-flavour opposite-sign pair with invariant mass consistent with the Z boson mass, jets tagged as originating from b-quarks and missing transverse momentum. 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 20.3 fb^-1. No excess beyond the Standard Model expectation is observed. Interpretations of the results are provided in models based on the direct pair production of the heavier top squark state (t2) followed by the decay to the lighter top squark state (t1) via t2 --> Z t1, and for t1 pair production in natural gauge-mediated supersymmetry breaking scenarios where the neutralino (chi1^0) is the next-to-lightest supersymmetric particle and decays producing a Z boson and a gravitino (G) via the chi1^0 --> Z G process.

欧洲核子研究中心大型强子对撞机（CERN-LHC）。本研究开展了针对直接顶夸克超伴子（Top Squark）对产生过程的搜寻，分析样本包含至少两个轻子（Lepton）的事例，其中存在同味异号轻子对，其不变质量与Z玻色子（Z Boson）质量相符，同时包含b夸克标记喷注与缺失横动量（Missing Transverse Momentum）。本分析使用大型强子对撞机ATLAS探测器（ATLAS Detector）于2012年采集的质子-质子碰撞数据完成，该数据的质心系能量√s=8 TeV，对应积分亮度（Integrated Luminosity）为20.3 fb⁻¹。本研究未观测到超出标准模型（Standard Model）预期的信号过剩。针对两类模型给出了本结果的解释：一类基于重质量顶夸克超伴子态（t₂）的直接对产生，随后重顶夸克超伴子通过衰变道t₂→Z t₁衰变至轻质量顶夸克超伴子态（t₁）；另一类针对自然规范传递型超对称破缺（Gauge-Mediated Supersymmetry Breaking）场景下的t₁对产生过程，该场景中中性微子（Neutralino，χ₁⁰）为次轻超对称粒子（Next-to-Lightest Supersymmetric Particle），并通过衰变道χ₁⁰→Z G产生Z玻色子与引力微子（Gravitino, G）。