Searches for lepton number and lepton flavour violating phenomena in high energy electroweak interactions with the ATLAS experiment

在ATLAS实验中，学生将使用完整的RUN-2质子-质子碰撞数据集，对高能弱电弱矢量玻色子融合/矢量玻色子散射相互作用中的一系列轻子数和轻子味道破坏现象进行新颖的搜索。第一份出版物将侧重于建立正在研究中的双介子终态的一般技术和模型，然后在随后的数据分析和出版物中探索双介子和混合轻子的终态。未来可能的扩展包括利用ATLAS和AFP光谱仪一起探索光子聚变相互作用中类似的新现象的研究计划的扩展。为了支持这些搜索，特别是tau和混合轻子的搜索，学生将在ATLAS实验中为RUN-3和HL-LHC升级数据获取阶段的tau重建和识别算法的增强做出贡献。特别是，学生将开发新的机器学习工具，将tau ID协调到一个算法中，对五种不同的衰减模式和多喷流背景进行分类，并最终提高性能。

The student will perform novel searches for a series of lepton number and lepton flavour violating phenomena in high-energy electroweak vector boson fusion / vector boson scattering interactions at the ATLAS experiment using the full Run-2 proton-proton collision dataset. The first publication will focus on establishment of the general techniques and models under study on the di-muon final state, before exploring di-tau and mixed lepton flavour final states in subsequent data analyses and publications. Potential future extensions include expansion of the research programme to probe similar new phenomena in photon-fusion interactions using ATLAS in conjunction with the AFP spectrometer.To support these searches, in particular the tau and mixed-lepton searches, the student will contribute to the enhancement of tau reconstruction and identification algorithms across the ATLAS experiment for Run-3 and HL-LHC upgrade data-taking phases. In particular, the student will develop new machine learning tools to harmonise tau ID into a single algorithm classifying five distinct decay modes and multijet backgrounds, and ultimately improve performance.