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Studies of the properties of the Higgs Boson

希格斯玻色子特性的研究

基本信息

批准号：
1937411
负责人：
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：
2017
资助国家：
英国
起止时间：
2017 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=studentship-1937411
关键词：
Studies properties Higgs Boson

项目摘要

The Standard Model of particle physics is a very successful theory, describing the fundamental constituents of matter and their interactions. In the past 40 years it has proven to be extremely accurate in predicting the results observed by our experiments, including the presence of the Higgs boson, discovered in 2012 by the ATLAS and CMS collaborations. Despite the great predictive power of the Standard Model, the prevailing theory of particle physics, there are phenomena which are not described by the theory, hinting that new physics must exist beyond the Standard Model, two examples are dark matter and dark energy.The thesis will report the results of performing precision measurements of the properties of the Higgs boson, in order to look for new physics beyond the Standard Model. Two examples are the mass and the width of the Higgs that provide a powerful test of the theory and their measurement are the principal goals of the thesis. Given the large dataset that ATLAS will collect in the next three years, the H->ZZ->4l channel will provide the most precise measurement of the Higgs mass, especially for the muon final states. This measurement, together with those of other Standard Model parameters such as the W boson and top quark masses, can be used to directly test the consistency of the Standard Model. Measuring the Higgs boson width provides extremely interesting information as it is sensitive to the decays of the Higgs boson to invisible particles. At the LHC this measurement is not directly possible, given that the expected width is about 4 MeV, almost three orders of magnitude smaller than the experimental resolution. A constraint on the width of the Higgs boson can, however, be extracted from the measurement of the "on-shell" and "off-shell" signal strengths in the H->ZZ->4l (2l2v) final states, if we assume that the couplings of the Higgs boson do not depend on the energy at which it is produced. The (2l2v) final state is also sensitive to new Higgs particles at higher mass that are predicted in theories that extend the Standard Model. A search for these new Higgs particles will also be made if sufficient time exists and the searches continue to be of interest experimentally and theoretically.In addition to the analysis of the proton-proton collision data, an ATLAS student must make a technical contribution to the experiment in order to be qualified for authorship. This is important for the education of the student and necessary for the experiment in order for it to remain operational and well-monitored. ATLAS is embarking on an ambitious upgrade of the detector and Ricardo will be involved in this through high statistics studies to understand the response of the 130 nm readout electronic ASICs for the silicon camera upgrade to ionizing radiation.

粒子物理学的标准模型是一个非常成功的理论，它描述了物质的基本成分及其相互作用。在过去的40年里，它被证明在预测我们实验观察到的结果方面非常准确，包括2012年ATLAS和CMS合作发现的希格斯玻色子的存在。尽管粒子物理学的主流理论--标准模型具有很强的预测能力，但仍有一些现象是标准模型所不能描述的，这暗示着在标准模型之外必然存在着新的物理，暗物质和暗能量就是其中的两个例子。本文将报道对希格斯玻色子的性质进行精确测量的结果，以寻找标准模型之外的新物理。两个例子是希格斯粒子的质量和宽度，这两个例子为理论提供了有力的检验，它们的测量是论文的主要目标。考虑到ATLAS将在未来三年内收集的大型数据集，H->ZZ->4l通道将提供对希格斯质量的最精确测量，特别是对μ子末态的测量。这个测量，连同其他标准模型参数如W玻色子和顶夸克质量的测量，可以用来直接检验标准模型的一致性。测量希格斯玻色子宽度提供了非常有趣的信息，因为它对希格斯玻色子衰变为不可见粒子很敏感。在大型强子对撞机上，这种测量是不可能的，因为预期的宽度约为4 MeV，比实验分辨率小了近三个数量级。然而，如果我们假设希格斯玻色子的耦合不依赖于它产生时的能量，则可以从H->ZZ->4l（2l 2 v）末态的“壳层上”和“壳层外”信号强度的测量中提取出对希格斯玻色子宽度的限制。（2l 2 v）终态也对新的更高质量的希格斯粒子敏感，这些粒子在扩展标准模型的理论中被预测。如果有足够的时间，并且在实验上和理论上对这些新的希格斯粒子继续感兴趣，也将进行搜索。除了质子-质子碰撞数据的分析外，ATLAS学生必须对实验做出技术贡献，才有资格获得作者资格。这对于学生的教育是重要的，对于实验是必要的，以便它保持运作和良好的监测。ATLAS正在着手对探测器进行雄心勃勃的升级，Ricardo将通过高统计研究参与其中，以了解硅相机升级的130 nm读出电子ASIC对电离辐射的响应。