Search for QCD Instantons at the LHC using the ATLAS detector

一系列悬而未决的实验和理论问题表明，标准模型并不是物质和力的最终理论。超对称性(SUSY)是标准模型最受欢迎的扩展之一，它解决了标准模型目前存在的许多问题。该理论预言，每个费米子都有一个玻色子伙伴，反之亦然。如果这种超对称配对粒子存在，它们的质量应该在TeV尺度上，并且应该在大型强子对撞机中产生，可以通过ATLAS找到。ATLAS最近发现的希格斯玻色子进一步增加了TeV尺度超对称性的动机。该研究计划扩展了对此类粒子的ATLAS搜索。目的：发现新的超对称伙伴，或对提出它们的理论模型施加严格的实验约束来探索结果的现象学后果目标：有助于ATLAS探测器的维护和操作改进LHC RUN-3的物理对象的触发或重建为一篇或多篇搜索论文提供一种或多种超对称模型中对这些结果的一种或多种解释该研究将使用最近完成的LHC的Run-2数据集以及最新的最先进的机器学习技术来提高灵敏度。它将扩展牛津ATLAS小组在其中发挥核心作用的最近结果，包括搜索西格西诺、夸克、斯普顿和胶子。在参数空间的某些区域，在收集了140/fb的积分光度之后，大型强子对撞机实验才开始达到比上一代LEPE+e实验更高的灵敏度。特别是在这些以低截面和压缩质谱图为特征的地区，预计大部分研究将集中在这些地区。其他可能性包括规范中介模型或违反R-奇偶校验的模型。任何公司或合作伙伴都参与了这项研究，并与我们的全球合作伙伴在CERN的ATLAS实验上进行了合作。阿特拉斯是大型强子对撞机的两个通用探测器之一。牛津小组对ATLAS探测器的建造作出了贡献，并继续在其运作中发挥核心作用，特别是在半导体追踪器、动量缺失触发算法以及喷气机、缺失动量和µ子的重建方面。

A range of unresolved experimental and theoretical issues suggest that the Standard Model is not the final theory of matter and forces. Supersymmetry (SUSY) is one example of a favoured extension of the Standard Model, and one which solves many of its current problems. The theory predicts that every fermion has a bosonic partner and vice-versa. If such supersymmetric partner particles exist, they ought to have masses at the TeV scale, and should be produced in the LHC and can be found by ATLAS. The recent discovery by ATLAS of a Higgs boson further increases the motivation for TeV-scale supersymmetry. This research programme extends the ATLAS searches for such particles.Aims:Discovery new supersymmetric partners, or place tight experimental constraints the theoretical models which propose themExplore the phenomenological consequences of the resultsObjectives:Contribute to the maintenance and operation of the ATLAS detectorImprove the triggering or reconstruction of physics objects for Run-3 of the LHCProvide a leading contribution to one or more search papersContribute to one or more interpretations of these results within supersymmetric modelsThe research will use the recently completed Run-2 dataset from the LHC together with the latest in state-of-the-art machine learning techniques to increase sensitivity. It will extend recent results in which the Oxford ATLAS group has had a central role, including searches for higgsinos, squarks, sleptons and gluinos. There are regions of parameter space in which the LHC experiments, after collectiong 140/fb of integrated luminosity are only starting to achieve sensitivity beyond the previous generation of LEP e+e- experiments. It is particularly in these regions, characterised for example by low cross-sections and compressed mass spectra, in which it is anticipated that the bulk of the research will be focused. Other possibilities include gauge-mediate models or models with R-parity violation.Any companies or collaborations involvedThe research is performed in collaboration with our global partners on the ATLAS experiment at CERN. ATLAS is one of two general-purpose detectors at the LHC. The Oxford group contributed to the construction of the ATLAS detector, and continues to be centrally involved in its operation, particularly in the semiconductor tracker, the missing-momentum trigger algorithms, and the reconstruction of jets, missing momentum and muons.