Search for QCD Instantons at the LHC using the ATLAS detector

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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.