"Table 6" 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）。本研究针对直接顶夸克超伴子（top squark）成对产生过程展开搜寻，分析所用事例包含至少两个轻子（lepton），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；同时样本包含被标记为b夸克（b-quark）起源的喷注（jet）以及横向缺失动量（missing transverse momentum）。本次分析采用大型强子对撞机ATLAS探测器（ATLAS detector）于2012年采集的质心系能量√s=8 TeV的质子-质子对撞数据，对应的积分亮度为20.3 fb⁻¹。研究未观测到超出标准模型（Standard Model）预期的信号过剩。针对本结果的物理解释基于两类超对称模型：其一为较重顶夸克超伴子态（t2）直接成对产生后，通过衰变道t2→Z t1衰变至较轻顶夸克超伴子态（t1）的模型；其二为自然规范传递超对称破缺（gauge-mediated supersymmetry breaking）情景下t1成对产生的模型，该情景中中性伴子（neutralino，χ₁⁰）为次轻超对称粒子，并通过衰变道χ₁⁰→Z G产生Z玻色子与引力微子（gravitino，G）。