J/ψ是粲夸克及其反粲夸克組成的束縛態(tài),是最簡單的量子色動力學QCD束縛態(tài)之一,是研究QCD的很好的探針。自1974年被發(fā)現(xiàn)以來,對其產生機制的實驗和理論就從未中斷過。J/ψ的產生過程通�？梢员粍澐譃閮蓚�子過程:粲夸克和反粲夸克對的產生以及夸克對演化成束縛態(tài)的過程。粲夸克對產生通常是具有較大四動量轉移的硬過程,可以通過微擾量子色動力學（pQCD）計算。而粲夸克對演化到J/ψ的過程是一個非微擾的軟過程,只能通過唯象模型來描述。目前在描述J/ψ產生的諸多模型中,比較成功的有色單態(tài)模型（CSM）,色蒸發(fā)模型（CEM）,以及色八重態(tài)模型（COM）。但目前沒有任何一個模型能夠同時描述所有的實驗測量結果。在實驗中觀測到的J/ψ,不僅包括由粲夸克對演化產生的直接貢獻,還包含從更高階的粲偶素和B介子衰變而來的貢獻,從而進一步加大了研究J/ψ產生機制的難度。此外,粲夸克對在強子對撞的產生并沒有被完全理解。ALICE合作組最近測量了在質子-質子7TeV對撞能量下粲夸克和J/ψ的產生隨帶電粒子多重數(shù)的變化。該結果顯示隨著帶電粒子多重數(shù)的增加,粲夸克和J/ψ產生相對于多重數(shù)有強于線性的增長,并且這種增長沒有橫... 

【文章來源】：中國科學技術大學安徽省 211工程院校 985工程院校

【文章頁數(shù)】：131 頁

【學位級別】：博士

【文章目錄】：
摘要
ABSTRACT
Chapter 1 Introduction
    1.1 The subatomic world
    1.2 Standard model
    1.3 Quantum chromodynamics
        1.3.1 Asymptotic freedom
        1.3.2 Color confinement
Chapter 2 J/ψ meson
    2.1 Charmonium
    2.2 J/ψ production mechanism
        2.2.1 Color singlet model
        2.2.2 Color evaporation model
        2.2.3 Non-relativistic QCD approach
        2.2.4 J/ψ polarization and reference frames
    2.3 Experimental measurements
        2.3.1 Feed down
        2.3.2 Cross section measurements
        2.3.3 Polarization measurements
    2.4 J/ψ production at partonic level
    2.5 Discussion and thesis scope
Chapter 3 Experimental Setup
    3.1 Relativistic Heavy Ion Collider
    3.2 STAR Detector
        3.2.1 Time Projection Chamber
        3.2.2 Barrel Electromagnetic Calorimeter （BEMC）
        3.2.3 Time of Flight
Chapter 4 Data analysis
    4.1 Analysis overview
    4.2 J/ψ analysis
        4.2.1 Dataset and Trigger
        4.2.2 Event Selection
        4.2.3 Track Selection
        4.2.4 Electron candiates
T J/ψ reconstruction">        4.2.5 High-p_T J/ψ reconstruction
        4.2.6 Acceptance and Efficiency
        4.2.7 Yield extraction and J/ψ detector efficiency
T spectrum measurement">        4.2.8 Systematic Uncertainty on J/ψ p_T spectrum measurement
    4.3 ψ（2S） analysis
        4.3.1 ψ（2S） analysis detials
        4.3.2 Systematic Uncertainty on ψ（2S） to J/ψ yield ratio measurement
    4.4 J/ψ production versus charged-particle multiplicity analysis
        4.4.1 Vertex finding algorithm in p+p events at STAR
        4.4.2 Charged-particle multiplicity measurement
        4.4.3 J/ψ measurement
        4.4.4 Efficiency and acceptance
        4.4.5 Systematic Uncertainty on J/ψ production versus charged-particle multiplicity
Chapter 5 Results and Discussion
T J/ψ Spectra">    5.1 High p_T J/ψ Spectra
    5.2 Measurement of the relative yields of ψ（2S） to J/ψ mesons
T scaling">    5.3 J/ψ x_T scaling
    5.4 J/ψ production as a function of charged-particle multiplicity
    5.5 Summary
Chapter 6 Outlook
    6.1 Detector Upgrades
        6.1.1 Inner Time Projection Chamber （iTPC） Upgrade
        6.1.2 End-cap Time of Flight （eTOF） Upgrade
    6.2 J/ψ relate physics
        6.2.1 J/ψ production in single-transverse-polarized proton-proton collisions
        6.2.2 J/ψ in the ultra peripheral proton-proton collision
References
ACKNOWLEDGMENTS
Presentations and Publication List



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