Search for Higgs boson decays to llγ with the CMS detector in proton-proton collisions at √s = 13 TeV with 137 fb-1

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姓名

李明晏(Ming-Yan Lee) 查詢紙本館藏

畢業系所

物理學系

論文名稱

(Search for Higgs boson decays to llγ with the CMS detector in proton-proton collisions at √s = 13 TeV with 137 fb-1)

相關論文

★ 利用CMS探測器量測7TeV下的Zγ產生截面	★ 以CMS 偵測器在質心質量為8TeV使用雙渺子和三秒子頻道尋找雙電荷希格斯玻色子
★ 在質子對撞能量8TeV下尋找具有雙電子雙渺子末態的激發態輕子	★ Measurement of Zγ production in 5 fb-1 of pp collisions at √s = 7 TeV with the CMS detector
★ Search for a Higgs boson decaying into γ∗γ → eeγ in pp collisions at √s = 8 TeV with the CMS detector	★ Measurement of Z boson production in the electron decay channel in p+Pb collisions at √sNN = 5.02 TeV with the CMS detector
★ 火花偵測器的製成	★ Search for the production of two Higgs bosons in the final state with two photons and two b quarks in proton-proton collision at √s = 13 TeV
★ Search for Exotic Decay of A Higgs Boson into A Dark Photon and a Standard Model Photon in pp Collisions at √s = 13 TeV	★ Search for a Higgs boson decay into γ*γ→μμγ in pp collisions at √s = 13 TeV
★ Search for the rare decays of Z and Higgs bosons to J/ψ plus photon at √s = 13 TeV	★ Measurement of Zγ production cross section in pp collisions at sqrt(s) = 13 TeV with the CMS detector
★ Search for H→Zγ→bbγ produced in association with a Z boson in proton-proton collisions at √s = 13 TeV with the CMS detector at the LHC	★ nono
★ TCAD simulation of silicon detector	★ Assembly and Beam Test Analysis of sPHENIX INTT Detector

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至系統瀏覽論文 (2025-7-31以後開放)

摘要(中)

本論文研究希格斯粒子衰變至Z玻色子及光子之衰變頻道，其中Z玻色子衰變至雙輕子，雙輕子在此為電子對與渺子對。本分析使用數據為大型強子對撞機之質子-質子對撞於中心質量13兆電子伏特收集於緊湊渺子線圈偵測器，對應光亮度為137fb-1。本分析使用動力學重整(kinematic refit)、終態光子復原 (final state radition photon recovery)及多變量分析 (MultiVariate Analysis)改善分析靈敏度，這些方法相較於以篩選條件為主的分析改善了24%的靈敏度。預測觀測上限在95%信心水準下，可得到1.7倍標準模型觀測值對應於顯著水準1.4 個標準差。

摘要(英)

This thesis describes the Higgs decays to dilepton plus one photon with dilepton from the Z pole. This analysis is performed using a dataset recorded by the CMS experiment at the LHC from proton-proton collisions at a center of mass energy of 13TeV corresponding to an integrated luminosity of 137 fb−1. This analysis inte- grated the kinematic refit, final state photon radiation recovery ,and multivariate analysis(MVA) methods to boost the sensitivity. These techniques bring a 24% improvement compare to the cutbased analysis. Limits are set on the cross-section of a standard model Higgs boson for 125GeV at 95% confidence level is about 1.7 times the standard model prediction for the expected results with the p-value corresponding 1.4σ.

關鍵字(中)

★ 大強子對撞機
★ 緊湊渺子偵測器
★ 希格斯粒子
★ 稀有希格斯衰變

關鍵字(英)

★ LHC
★ CMS
★ Higgs
★ rare decay

論文目次

1 Introduction and theory overview 1
1.1 StandardModel............................... 1
1.1.1 Gauge theory of electromagnetic field........ 4
1.1.2 Electroweak theory......................... 5
1.1.3 Higgs mechanism.......................... 7
1.2 Higgs production and decays at LHC .................. 9
1.3 H→Zγ→llγ............................... 12
1.3.1 Theoretical aspects ......................... 12
1.3.2 Review for previous results .................... 14
2 Experimental apparatus 17
2.1 LargeHadronCollider ........................... 17
2.2 CompactMuonSolenoid.......................... 21
2.2.1 Superconducting solenoid..................... 23
2.2.2 Trackersystem ........................... 24
2.2.3 Electromagnetic Calorimeter ................... 25
2.2.4 Hadronic Calorimeter ....................... 26
2.2.5 Muon System ............................ 27
2.2.6 Trigger System ........................... 29
3 Analysis strategies 31
3.1 Datasets and Simulation .......................... 32 3.1.1 Data samples ............................ 32
3.1.2 MC samples............................. 32
3.1.3 Pileup reweighting......................... 35
3.1.4 Photon internal conversion .................... 36
3.2 EventSelections............................... 39
3.2.1 Triggers ............................... 39
3.2.2 Muons................................ 44
3.2.3 Electrons............................... 46
3.2.4 Photons ............................... 47
3.2.5 Summary of selections....................... 50
3.3 Final state radiation recovery ....................... 54
3.4 Kinematic fit................................. 55
3.5 Kinematic MVA ............................... 58
3.5.1 Training setup............................ 58
3.5.2 Training variables.......................... 58
3.5.3 Validation .............................. 62
3.6 DijetMVA .................................. 62
3.6.1 Training setup............................ 70
3.6.2 Training variables.......................... 71
3.6.3 Validation .............................. 71
3.7 EventCategorization ............................ 78
3.7.1 Criteria for lepton tag category .................. 79
3.7.2 Determination and criteria of dijet categories.......79
3.7.3 Determination and criteria of untagged categories.....80
3.7.4 Investigation and dropping of boosted category.......83
3.7.5 Improvement compared to cut-based analysis..........86
3.8 Signal and background modeling..................... 86
3.8.1 Signal modeling........................... 87
3.8.2 Resonant background modeling ................. 88
3.8.3 Nonresonant background modeling ............... 88
3.9 Uncertainties................................. 91
3.9.1 Theoretical uncertainties...................... 91
3.9.2 Normalization uncertainty .................... 92
3.9.3 Shape uncertainties......................... 96
3.9.4 Correlation between different datasets.............97
4 Results and summary 111
4.1 Results ....................................111
4.2 Conclusion..................................113
A llγ pT reweighting 121
B L1 prefire problem 123
C MVA variables validation 125
C.1 2017 kinematic MVA variables.......................125
C.2 2018 kinematic MVA variables.......................132
C.3 2017 Dijet MVA variables..........................138
C.4 2018 Dijet MVA variables..........................138
C.5 Shower shape corrections .........................146
C.5.1 Valiation with Z to ee........................146
C.5.2 Valiation with Z→μμγ ......................146
D FitStudies 159
D.1 Bias Study ..................................159
D.2 Fit Range Study ...............................160
D.3 Sideband fTest study ............................162
D.4 MCFitStudy.................................162
E Electron performance for 2017 data 173
E.1 Electron reconstruction...........................173
E.2 Electron performance............................174

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指導教授

郭家銘(Chia-Ming Kuo)

審核日期

2020-7-29

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