ATLAS实验中含轻子末态squark，gluino及含tau末态gaugino粒子的寻找

Supersymmetry (SUSY) is one of the most popular theories for beyond standard model particle physics. The lightest SUSY particle provides itself as an excellent dark matter candidate. The SUSY search, except being significant to the SUSY theory, also has a large impact on the search of dark matter evidence. The search for SUSY particles is on the top list of the physics goals for the large hardron collider (LHC) at CERN. Strongly produced SUSY particles are with relative larger cross-section, the study of which provides the most sensitive analysis in the SUSY search. The electroweak SUSY search usually benefits from the relative lower background. The goal of this project is to perform two searches using 13/14 TeV data collected at LHC with the ATLAS detector: a search for strongly produced squarks and gluinos in events with isolated leptons and a search for electroweakly produced gauginos in final states with hadronically decaying taus.

超对称理论(SUSY)是超出标准模型粒子物理新理论最热门的理论之一。最轻的超对称粒子是暗物质非常好的候选者。超对称粒子的寻找，不仅对超对称粒子本身有重要意义，也对暗物质实验证据的寻找具有重要影响。超对称粒子的寻找是欧洲核子中心(CERN)大型强子对撞机(LHC)实验最重要的物理目标之一。强相互作用的超对称粒子具有较大的产生截面，是超对称物理研究中信号敏感度最高的分析。弱相互作用的超对称物理分析包含相对较小的本底，有利于超对称粒子的寻找。本课题将基于LHC实验在13/14TeV质心能量所产生的对撞数据，使用ATLAS探测器，开展强相互作用下含轻子末态squark，gluino粒子的寻找以及弱相互作用下含tau末态gaugino粒子的寻找。

本项目基于欧洲核子中心CERN的大型强子对撞机LHC上的ATLAS实验对超对称粒子进行探寻。课题执行期间，使用LHC的Run1所有数据（20.3fb-1）进行电弱超对称8TeV能量下的总结性研究；使用Run2阶段首批3.2fb-1数据对含轻子末态gluino进行首次13TeV能量研究；使用Run2中期数据（36.1fb-1）对含轻子末态squark，gluino及含tau末态gaugino粒子进行深入研究。最新的研究没有观测到超出标准模型的预期。在neutralino1质量很轻的情况下，gluino质量上限可被排除到约2.1TeV，squark质量上限可被排除到约1.25TeV，chargino/neutralino2联合质量上限已被排除到约760GeV。