The search for pair production of Higgs Bosons at the ATLAS experiment

在 ATLAS 实验中寻找希格斯玻色子的配对产生

• 批准号: 2275245
• 金额: --
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2275245
• 关键词: search; pair; production; Higgs; Bosons

The aim of Iza's PhD project is to accomplish world-leading analyses looking for new phenomena and constraining the value of the Higgs self-coupling using di-Higgs production, specifically the four b-quark final state.Higgs boson pair production is a critical channel, sensitive to many new physics phenomena and modifications to the Higgs sector, and also an important measurement of the Higgs self-coupling and the extended Higgs potential. Though a full measurement may need the full luminosity of the High Luminosity LHC, the large Run-2 datasets are sensitive probes, already able to constrain this vital coupling.Iza will work within the Oxford ATLAS Exotics group in the department and also will collaborate and work in the respective analysis groups within the ATLAS collaboration. She will focus on analysing ATLAS data from LHC Run-2 (2015-2018) for evidence of di-Higgs production. Working on the di-Higgs decay to four b-quarks, she will search for evidence of new resonant and non-resonant phenomena. An important aspect of the latter will be to understand and improve how different values of the Higgs self-coupling can be constrained using the large datasets now available. She will also work on the combination of the Run-2 search channels, the most sensitive of which are 4b, bbtautau, bbyy and bblnulnu. The combination of these channels, each using the full 140 fb-1 of Run-2 data (nearly four times that of the best previous result) will allow for much more powerful constraints on the SM coupling, or provide evidence of a non-SM coupling value. This is a major undertaking, requiring a great deal of effort from contributors working on each of the analysis channels to understand their relative sensitivities and contributions. She will need to understand the systematic and statistical correlations within the different channels and develop tools that properly account for them in this particular analysis. In particular, there has been a lot of theoretical progress, resulting in more precise predictions and ability to model BSM physics in an effective field theory approach, which will require considerably more work to understand fully, and optimise both the sensitivity and visualisation of the results.To improve the sensitivity to final states containing Higgs decays to b-quark pairs, she will need to calibrate and develop new, advanced b-quark identification algorithms. She will work on means of calibrating b-tagging algorithms in-situ, using samples of high-pT gluon splitting to bb to provide correction factors in this topology directly. Dedicated advanced b-hadron taggers using machine learning techniques are being developed which gain significant performance. Often these cannot be calibrated by conventional means, but these techniques may provide an alternative route, improving Higgs jet tagging across the ATLAS physics programme.This work will leave her ideally placed to analyse the first Run-3 data due in 2021 and 2022, at a new record collision energy of 14 TeV. She will be able to ensure that b-tagging is as performant as possible, which will be vital for world-leading analyses using large luminosities of Run-3 data in this signature. She will spend her second year at CERN to be as close as possible to the laboratory and data-taking, and to gain visibility within the ATLAS Collaboration.

IZA博士项目的目的是完成寻找新现象的世界领先的分析，并使用di-higgs生产来限制希格斯自我耦合的价值，特别是四个B Quark最终状态。-毫无疑问的玻色子对生产是至关重要以及扩展的希格斯潜力。尽管完整的测量可能需要高光度LHC的全部亮度，但大型RUN-2数据集是敏感的探针，已经能够限制这一重要的耦合。IIZA将在该部门的牛津Atlas Exotics组中起作用，并且还将在ATLAS协作中的各个分析组中协作和工作。她将专注于分析来自LHC Run-2（2015-2018）的ATLAS数据，以证明Di-Higgs生产的证据。她将在di-higgs衰减到四个B Quarks时，她将寻找新的共振和非共振现象的证据。后者的一个重要方面是了解和改善如何使用现在可用的大型数据集来限制HIGGS自耦合的不同值。她还将在Run-2搜索频道的结合下进行工作，其中最敏感的是4B，BBTAUTAU，BBYY和BBLNULNU。这些通道的组合，每种频道使用RUN-2数据的整个140 FB-1（几乎是最佳先前结果的四倍）将允许在SM耦合上产生更强大的约束，或提供非SM耦合值的证据。这是一项重大的事业，需要从研究每个分析渠道的贡献者那里做大量努力，以了解其相对敏感性和贡献。她将需要了解不同渠道内的系统和统计相关性，并开发在此特定分析中正确说明它们的工具。特别是，在有效的现场理论方法中，有很多理论上的进步，从而产生了更精确的预测和对BSM物理进行建模的能力，这将需要更多的工作才能充分理解，并优化了结果的敏感性和可视化。以提高对最终状态的敏感性，对最终状态含有HIGG的含量，从而使Higgs衰减均需要校准，并需要进行校准，并进行了校准。她将使用高PPLUON分裂的样品对BB进行校准，以校准B标记算法，直接在此拓扑中提供校正因子。使用机器学习技术的专用高级B-HADRON标记器正在开发出可观的性能。通常，这些技术无法通过常规手段进行校准，但是这些技术可能会提供一条替代路线，改善Higgs跨Atlas Physics Programme的Jet标记。这项工作将使她理想地分析2021年和2022年应付款的第一个Run-3数据，并以14 TEV的新唱片碰撞能量为14 TEV。她将能够确保B-Tagging具有尽可能的性能，这对于使用此签名中的Run-3数据的较大仪表进行了世界领先的分析至关重要。她将在CERN度过第二年，以尽可能接近实验室和数据研究，并在Atlas合作中获得可见性。