2012年,希格斯玻色子(Higgs)由大型強子對撞機(LHC)上的ATLAS和CMS實驗組通過研究雙玻色子衰變道而發(fā)現(xiàn)。該粒子的發(fā)現(xiàn)完善了標準模型理論并開啟了粒子物理研究的新時代。在此之后,為了檢驗所發(fā)現(xiàn)的Higgs是否與標準模型預言相穩(wěn)合,實驗物理學家開展了多項針對Higgs性質的研究,其中包括對Higgs量子數(shù)以及其與費米子耦合常數(shù)的測量。盡管標準模型可以成功地解釋當前大多數(shù)存在的粒子以及現(xiàn)象,但它并不是一個完美的理論框架,仍然有一些觀測到的現(xiàn)象無法用標準模型理論解釋,例如中微子的質量,暗物質以及正反物質不對稱等等。因而,尋找超越標準模型的新物理現(xiàn)象也是當前非常重要的研究課題。經過兩年多的停機,2015年,LHC在質心系能量提高到13 TeV之后重新開啟了第二階段的取數(shù)(Run 2)。伴隨著質心系能量的提高,相關物理過程的產生截面都有著顯著的增加,從而為探索Higgs的稀有衰變道以及尋找TeV能區(qū)下的新物理現(xiàn)象提供了很好的契機。隨后經過2015和2016兩年的成功運行,LHC上的ATLAS探測器收集到了積分亮度為36.1 fb-1的大量數(shù)據。本論文所闡述的兩項研究工作即是利用這些...

【文章頁數(shù)】：173 頁

【學位級別】：博士

【文章目錄】：
摘要
Abstract
Acknowledgements
Chapter 1 Introduction
Chapter 2 Theory
    2.1 The Standard Model of particle physics
        2.1.1 Elementary particles in the Standard Model
        2.1.2 Theoretical formalism of the Standard Model
        2.1.3 The Higgs mechanism
    2.2 The Related Theories Beyond the Standard Model
        2.2.1 Sequential Standard Model
        2.2.2 E₆-motivated Z' models
        2.2.3 Contact interactions
    2.3 Physics at the Large Hadron Collider
        2.3.1 Phenomenology of hadronic collision
        2.3.2 Higgs boson production at the LHC
Chapter 3 The Large Hadron Collider and the ATLAS Detector
    3.1 The Large Hadron Collider
        3.1.1 General introduction of the Large Hadron Collider
        3.1.2 Luminosity and pile-up
    3.2 The ATLAS Detector
        3.2.1 Physics requirements and detector overview
        3.2.2 Magnet system
        3.2.3 Inner Detector
            3.2.3.1 Pixel detector
            3.2.3.2 The semiconductor tracker
            3.2.3.3 Transition radiation tracker
        3.2.4 Calorimeters
            3.2.4.1 LAr electromagnetic calorimeter
            3.2.4.2 Hadronic calorimeters
        3.2.5 Muon Spectrometer
            3.2.5.1 Monitored drift tube chambers
            3.2.5.2 Cathode strip chambers
            3.2.5.3 Resistive plate chambers
            3.2.5.4 Thin gap chambers
        3.2.6 Forward detectors
        3.2.7 Trigger system
            3.2.7.1 Level-1 Trigger
            3.2.7.2 High-level trigger
Chapter 4 Simulation and Object Reconstruction for the ATLAS Experiment
    4.1 Detector Simulation
        4.1.1 Event generation
        4.1.2 Detector simulation
        4.1.3 Digitization
    4.2 Object Reconstruction
        4.2.1 Track
            4.2.1.1 Inner detector track
            4.2.1.2 Muon spectrometer track
        4.2.2 Primary vertex
        4.2.3 Electron
            4.2.3.1 Electron reconstruction
            4.2.3.2 Electron identification
            4.2.3.3 Electron isolation
        4.2.4 Muon
            4.2.4.1 Muon reconstruction
            4.2.4.2 Muon identification
            4.2.4.3 Muon isolation
            4.2.4.4 Muon momentum scale and resolution
            4.2.4.5 Impact of ID-MS alignment on high pT muon resolution
        4.2.5 Jet
            4.2.5.1 Jet reconstruction
            4.2.5.2 Jet energy scale calibration
            4.2.5.3 b-jet tagging
        4.2.6 Missing transverse energy
Chapter 5 Search for Standard Model Higgs Boson with the Dimuon Final State
    5.1 Introduction
    5.2 Data and MC samples
    5.3 Object and Event Selection
        5.3.1 Object level selection
            5.3.1.1 Muons
            5.3.1.2 Jets
            5.3.1.3 Electrons
            5.3.1.4 ET
miss

            5.3.1.5 Overlap removal between objects
        5.3.2 Event level selection
            5.3.2.1 Z control region
            5.3.2.2 Z plus two jets control region
            5.3.2.3 Data/MC comparisons for the kinematic variables in thesignal region
    5.4 Categorization for the Signal Region
        5.4.1 Selection for the VBF enriched categories
        5.4.2 Selection for the ggF enriched categories
        5.4.3 Event yields in eight signal categories
    5.5 Signal and Background Modeling
        5.5.1 Signal modeling
        5.5.2 Background modeling
    5.6 Systematic Uncertainties
        5.6.1 Theoretical uncertainties on the signal
        5.6.2 Experimental uncertainties on the signal
        5.6.3 Spurious signal uncertainty from the background modeling
    5.7 Statistical Analysis
    5.8 Results
Chapter 6 Search for New Phenomena with the Dilepton Final State
    6.1 Introduction
    6.2 Monte Carlo Samples
        6.2.1 Background samples
        6.2.2 Signal samples
    6.3 Event Selection
        6.3.1 Electron channel
        6.3.2 Muon channel
    6.4 Background Estimation and Kinematic Distributions
        6.4.1 Background estimation
        6.4.2 Kinematic distributions
    6.5 Systematic Uncertainties
    6.6 Statistical Analysis
        6.6.1 Log-likelihood ratio test
        6.6.2 Exclusion limits with Bayesian approach
    6.7 Results
Chapter 7 Summary and Outlook
Bibliography



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