RHIC-STAR 500 GeV质子-质子对撞中J/ψ的测量
发布时间：2021-02-19 20:41
J/ψ是粲夸克及其反粲夸克组成的束缚态,是最简单的量子色动力学QCD束缚态之一,是研究QCD的很好的探针。自1974年被发现以来,对其产生机制的实验和理论就从未中断过。J/ψ的产生过程通常可以被划分为两个子过程:粲夸克和反粲夸克对的产生以及夸克对演化成束缚态的过程。粲夸克对产生通常是具有较大四动量转移的硬过程,可以通过微扰量子色动力学（pQCD）计算。而粲夸克对演化到J/ψ的过程是一个非微扰的软过程,只能通过唯象模型来描述。目前在描述J/ψ产生的诸多模型中,比较成功的有色单态模型（CSM）,色蒸发模型（CEM）,以及色八重态模型（COM）。但目前没有任何一个模型能够同时描述所有的实验测量结果。在实验中观测到的J/ψ,不仅包括由粲夸克对演化产生的直接贡献,还包含从更高阶的粲偶素和B介子衰变而来的贡献,从而进一步加大了研究J/ψ产生机制的难度。此外,粲夸克对在强子对撞的产生并没有被完全理解。ALICE合作组最近测量了在质子-质子7TeV对撞能量下粲夸克和J/ψ的产生随带电粒子多重数的变化。该结果显示随着带电粒子多重数的增加,粲夸克和J/ψ产生相对于多重数有强于线性的增长,并且这种增长没有横...
【文章来源】：中国科学技术大学安徽省 211工程院校 985工程院校
【文章页数】：131 页
【学位级别】：博士
【文章目录】：
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-pT 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 pT 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 pT J/ψ Spectra
5.2 Measurement of the relative yields of ψ（2S） to J/ψ mesons
T scaling"> 5.3 J/ψ xT 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
本文编号：3041659
【文章来源】：中国科学技术大学安徽省 211工程院校 985工程院校
【文章页数】：131 页
【学位级别】：博士
【文章目录】：
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-pT 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 pT 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 pT J/ψ Spectra
5.2 Measurement of the relative yields of ψ（2S） to J/ψ mesons
T scaling"> 5.3 J/ψ xT 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
本文编号：3041659
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