Measurement of the Production of the Standard Higgs Boson As

发布时间：2021-08-01 05:28

　　希格斯场是粒子物理标准模型的重要组成部分,它不仅负责产生基本粒子的质量,同时它也是标准模型中唯一的标量粒子。因此对于希格斯玻色子的研究成为了大型强子对撞机（LHC）实验中的一个热门课题。大型强子对撞机给我们提供了一个绝好的机会来研究标准模型的预言以及寻找超越标准模型的新物理现象。在新物理理论中通常会包含一个更加复杂的希格斯场,因此会产生更多的希格斯波色子,例如一个带电的希格斯玻色子。寻找这种新粒子将是对新物理模型的一个直接验证。本博士论文共包含了两部分主要贡献:在顶夸克和底夸克衰变道寻找带电希格斯玻色子（H+→tb）;在多轻子末态寻找标准模型希格斯玻色子伴随一对顶夸克产生的过程（ttH）。寻找带电希格斯玻色子的分析使用了ATLAS探测器在2015和2016年收集到的质心系能量13 TeV的质子质子对撞数据,对应的积分亮度为36.1 fb-1。分析在200 GeV到2000 GeV质量区间没有发现相对于标准模型背景的明显超出,相对于标准模型预言的最大偏离位于300 GeV质量点,对应的本地p0值为1.13%。寻找ttH产生的分析使用了 ATLAS探测器在2015年到2017年收集到的数据... 

【文章来源】：山东大学山东省 211工程院校 985工程院校 教育部直属院校

【文章页数】：207 页

【学位级别】：博士

【文章目录】：
摘要
ABSTRACT
Chapter 1 Introduction
Chapter 2 Theory of scalar fields
    2.1 The Standard Model and Higgs Mechanism
        2.1.1 Introduction
        2.1.2 Theory of the Standard Model
            2.1.2.1 Quantum electrodynamics
            2.1.2.2 Quantum chromodynamics
            2.1.2.3 Weak interactions
            2.1.2.4 Higgs mechanism
        2.1.3 SM Higgs boson production and decay at LHC
    2.2 Higgs sector beyond the Standard Model
        2.2.1 Introduction
        2.2.2 Two Higgs doublet model
Chapter 3 LHC & the ATLAS Detector
    3.1 The Large Hadron Collider
    3.2 The ATLAS Detector
        3.2.1 The ATLAS coordinate system
        3.2.2 Inner tracking detector
            3.2.2.1 Pixel detector
            3.2.2.2 Semiconductor tracker (SCT)
            3.2.2.3 Transition Radiation Tracker(TRT)
        3.2.3 Calorimeter
            3.2.3.1 Electromagnetic calorimeter
            3.2.3.2 Hadronic calorimeter
        3.2.4 Muon spectrometer
            3.2.4.1 Muon precision detectors
            3.2.4.2 Muon trigger detectors
        3.2.5 Trigger
        3.2.6 Magnetic systems
        3.2.7 Simulation of ATLAS detectors
    3.3 Upgrade of Inner Detector towards High-Luminosity LHC(HL-LHC): the Inner Tracker project (ITk)
    3.4 Object reconstruction
        3.4.1 Electrons
            3.4.1.1 Reconstruction
            3.4.1.2 identification
        3.4.2 Photons (γ)
        3.4.3 Muons
            3.4.3.1 Reconstruction
            3.4.3.2 Identification
        3.4.4 The (τ) lepton
        3.4.5 Jets
            3.4.5.1 Reconstruction
            3.4.5.2 Calibration and Systematics
            3.4.5.3 b-jets tagging
        3.4.6 Missing transverse energy
Chapter 4 Search for a heavy charged Higgs boson decaying totop and bottom quarks
    4.1 Introduction
    4.2 Overview of previous results
    4.3 Analysis strategy
        4.3.1 Data, Signal and background modelling
            4.3.1.1 Data samples
            4.3.1.2 Signal samples
            4.3.1.3 Background samples
        4.3.2 Selections
        4.3.3 Background estimation
        4.3.4 Multivariate analysis
            4.3.4.1 Brief concepts of BDT
            4.3.4.2 Classification BDT in di-lepton final states
    4.4 Mass reconstrution in di-lepton final states
        4.4.1 Introduction
        4.4.2 Reconstruction BDT Training
        4.4.3 Application to the analysis
    4.5 Results
        4.5.1 Systematic uncertainties
            4.5.1.1 Instrumental uncertainties
            4.5.1.2 Theoretical uncertainties
        4.5.2 Statistical study
            4.5.2.1 Statistical model
            4.5.2.2 Fit results
            4.5.2.3 interpretation
            4.5.2.4 CMS results
Chapter 5 Search for the production of Higgs boson associatedwith a pair of top quarks in multilepton final states
    5.1 Introduction
    5.2 Personal contributions
    5.3 Analysis strategy of ttH multilepton with 80 fb-1 Data
        5.3.1 Data and Monte Carlo samples
        5.3.2 Signal region definition and signal extraction
        5.3.3 MVA analysis
            5.3.3.1 2lSS 2D analysis strategy
            5.3.3.2 3l multiclass BDT
        5.3.4 Background estimate
            5.3.4.1 Template fit
    5.4 Study of 2lSS+1τ_(had) final state
        5.4.1 Event selection
        5.4.2 Categories analysis optimization
            5.4.2.1 Validation of categorization optimization
        5.4.3 Non-prompt backgrounds
            5.4.3.1 Electron charge flip (QMisID)
            5.4.3.2 Fake tau
            5.4.3.3 Fake light leptons
                5.4.3.3.1 Fake factor
                5.4.3.3.2 Matrix method
                5.4.3.3.3 Template fit
        5.4.4 Statistical interpretation
            5.4.4.1 Choice of analysis configurations
            5.4.4.2 Previous results
            5.4.4.3 Current results
            5.4.4.4 Alternative approach
            5.4.4.5 Summary
    5.5 Results of ttH multilepton analysis
        5.5.1 Comparison with CMS results
Chapter 6 Conclusion
Bibliography
致谢
附件



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