"Table 13" 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.

CERN-LHC。本研究呈现了顶超夸克（top squark）成对直接产生过程的搜寻分析，所用事件样本包含至少两个轻子，其中存在一对同味异号轻子对，其不变质量与Z玻色子（Z boson）质量相符，同时包含被标记为起源于b夸克（b-quark）的喷注与缺失横向动量（missing transverse momentum）。
本分析基于2012年大型强子对撞机（LHC）上ATLAS探测器（ATLAS detector）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20.3 fb⁻¹。
未观测到超出标准模型（Standard Model）预期的信号超额。
针对该结果的解释基于两类超对称模型：其一为重顶超夸克态（t2）的成对直接产生，随后重顶超夸克通过衰变道t2→Z t1衰变为轻顶超夸克态（t1）；其二为轻顶超夸克（t1）的成对产生，该情景属于自然规范传递超对称破缺模型，其中中性微子（neutralino，χ₁⁰）为次轻超对称粒子，通过衰变道χ₁⁰→Z G产生Z玻色子与引力微子（gravitino，G）。