Measurement of bottomonium production in pp and PbPb collisions at √sNN = 5.02 TeV with the CMS detector
- 주제(키워드) Quark-Gluon Plasma , CMS , LHC , Quarkonia , Bottomonia , Upsilon , Heavy-ion collision
- 발행기관 고려대학교 대학원
- 지도교수 홍병식
- 발행년도 2020
- 학위수여년월 2020. 2
- 학위구분 박사
- 학과 대학원 물리학과
- 세부전공 원자핵물리학전공
- 원문페이지 162 p
- UCI I804:11009-000000127044
- DOI 10.23186/korea.000000127044.11009.0000946
- 본문언어 영어
- 제출원본 000046025061
초록/요약
A high-density QCD medium consists of the deconfined quarks and gluons (the Quark-Gluon Plasma, QGP) is expected to be created in heavy-ion collisions at the Large Hadron Collider (LHC). As bottomonia are powerful tools to study the properties of such a matter, cross sections and nuclear modification factors of $\Upsilon(1S)$, $\Upsilon(2S)$ and $\Upsilon(3S)$ mesons have been studied proton-proton (pp), and lead-lead (PbPb) collisions at $\sqrt_{s_{NN}}$ = 5.02 TeV using the Run II data taken in 2015 with the Compact Muon Solenoid (CMS) detector at LHC. The nuclear modification factors are computed by the yield ratios of the PbPb and pp data as functions of the transverse momentum ($p_{T}$), rapidity (y), and collision centrality in PbPb. Strong suppression is observed for all three states, consistent with the sequential ordering scenario, $R_{AA}(\Upsilon(1S)) > R_{AA}(\Upsilon(2S)) > R_{AA}(\Upsilon(1S))$. In general, the suppression of $\Upsilon(1S)$ at 5.02 TeV is larger than that at 2.76 TeV, although the two results are compatible within the uncertainties. The upper limit on the $R_{AA}$ of $\Upsilon(3S)$ integrated over $p_{T}$, rapidity and centrality is 0.096 in 95% confidence level.
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Contents
Abstract
Contents i
List of Figures v
List of Tables xv
1 Introduction 1
2 Theoretical foundations 3
2.1 Quantum choromodynamics (QCD) ..................... 3
2.1.1 Quantum choromodynamics and asymptotic freedom . . . . . . . . 3
2.1.2 QCD phase diagram and Quark-Gluon Plasma . . . . . . . . . . . 4
2.2 Heavy Ion Collisions .............................. 9
2.2.1 Heavy-ion Collisions .......................... 9
2.2.2 Space-Time Evolution ......................... 9
2.3 Quarkonia and heavy quarks ......................... 12
2.3.1 Quarkonia................................ 12
2.3.2 Heavy-flavor Production........................ 12
2.3.3 Quarkonia at zero temperature .................... 14
2.3.4 Quarkonium Production........................ 18
2.4 Quarkonium modification in QGP ...................... 24 i
2.4.1 Quarkonium in QGP.......................... 24
3 Experimental setup 35
3.1 Large Hadron Collider (LHC)......................... 35
3.1.1 The Large Hadron Collider (LHC) .................. 35
3.2 Compact Muon Solenoid (CMS) ....................... 38
3.2.1 General Overview ........................... 38
3.2.2 Inner Tracking ............................. 38
3.2.3 Electromagnetic Calorimeter (ECAL) . . . . . . . . . . . . . . . . 40
3.2.4 Hadron Calorimeter (HCAL) ..................... 42
3.2.5 Muon System.............................. 43
3.3 Trigger...................................... 47
3.3.1 Data Acquisition (DAQ) System ................... 47
3.3.2 Level-1 (L1) Trigger .......................... 48
3.3.3 High-Level Trigger (HLT) ....................... 49
3.3.4 Muon HLT Trigger........................... 49
3.4 Muon Offline Reconstruction ......................... 50
3.4.1 Muon Identification .......................... 51
4 Analysis Procedure 55
4.1 Event Selection................................. 55
4.1.1 Datasets and muon triggers ...................... 55
4.1.2 Monte Carlo (MC) samples ...................... 57
4.1.3 Centrality determination........................ 59
4.1.4 Muon selection ............................. 59
4.2 Signal Extraction................................ 62
4.2.1 Fitting Overview............................ 62
4.2.2 Analysis binning ............................ 62
4.2.3 PDF Modeling ............................. 63
4.3 Correction factors ............................... 74
4.3.1 Reweight of MC for transverse momentum distribution . . . . . . . 74
4.3.2 Acceptance ............................... 79
4.3.3 Efficiency ................................ 81
4.4 Systematic Uncertainties............................ 83
4.4.1 Uncertainties from signal extraction ................. 83
4.4.2 Uncertainties from Correction Factors . . . . . . . . . . . . . . . . 84
4.4.3 Global Uncertainties.......................... 86
4.4.4 Total Systematic Uncertinties..................... 86
5 Results 93
5.1 Physics Observables .............................. 93
5.1.1 Upper limit extraction for cross section and RAA . . . . . . . . . . 94
5.2 DifferentialCrossSection ........................... 97
5.3 NuclearmodificationfactorRAA ....................... 99
5.4 Comparisons .................................. 106
5.4.1 Theory Comparisons.......................... 106
5.4.2 Comparison with other experiment.................. 108
5.4.3 Comparison with Charmonia ..................... 110
6 Summary and Conclusion 115
Bibliography 119
Acknowledgement