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| DC 欄位 | 值 | 語言 |
|---|---|---|
| dc.contributor.advisor | 熊怡(Yee Hsiung) | |
| dc.contributor.author | Meng-Lin Wu | en |
| dc.contributor.author | 吳孟霖 | zh_TW |
| dc.date.accessioned | 2021-06-12T18:07:06Z | - |
| dc.date.available | 2008-01-02 | |
| dc.date.copyright | 2008-01-02 | |
| dc.date.issued | 2007 | |
| dc.date.submitted | 2007-12-27 | |
| dc.identifier.citation | [1] HyperCP Collaboration, H. Park et al., Evidence for the decay
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| dc.identifier.uri | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/27493 | - |
| dc.description.abstract | 本論文尋找可能的中性K介子衰變至pi0介子以及輕準純量
sgoldstino(代稱X粒子)。所使用數據來自日本國家高能加速器 中心質子加速器的E391a 偵測器，於九十四年二月至三月間取 得。 經由事例重建，我們針對四組可能的質量範圍搜尋，並無發 現顯著訊號，因此給予90%信心水準之衰變分率上限，分別為 Br(KL->pi0X(181.7 MeV)) < 2.26e-6 Br(KL->pi0X(198.0 MeV)) < 1.97e-6 Br(KL->pi0X(214.3 MeV)) < 1.81e-6 Br(KL->pi0X(230.6 MeV)) < 1.17e-6 | zh_TW |
| dc.description.abstract | With mX = 214.3 MeV as hinted by a previous HyperCP
experiment, we report the first search of the decay KL->pi0X using the Run2 data sample recorded with the E391a detector at KEK-PS. The particle X has a theoretical interpretation as the pseudoscalar sgoldstino. It is predicted to decay predominantly to two photons. As a result of this search, we set a 90% confidence-level upper limit for its branching ratio at B(KL->pi0X)<1.81e-6. We also performed a search for the same mode assuming different mX: 181.7MeV, 198MeV, 230.6MeV and set respective 90% confidence-level upper limits: B(KL->pi0X181.7)<2.26e-6, B(KL->pi0X198.0)<1.97e-6 and B(KL->pi0X230.6)<1.17e-6. The KL flux for the E391a Run2 data set is also measured to be (4.83+-0.21)e9 in the fiducial region. | en |
| dc.description.provenance | Made available in DSpace on 2021-06-12T18:07:06Z (GMT). No. of bitstreams: 1 ntu-96-R94222025-1.pdf: 4403180 bytes, checksum: 41b23023e62c09ada07f0d44d693fe45 (MD5) Previous issue date: 2007 | en |
| dc.description.tableofcontents | Introduction 1
1.1 The X particle - HyperCP experiment . . . . . . . . . . . . . 1 1.2 The sgoldstino interpretation . . . . . . . . . . . . . . . . . . 1 1.3 The Higgs boson interpretation . . . . . . . . . . . . . . . . . 4 1.4 Hints at decay K0L ! 0X(X ! ) - KTeV and NA48 experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.5 K mesons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.6 Thesis outline . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2 KEK E391a 8 2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.2 The Neutral Beam . . . . . . . . . . . . . . . . . . . . . . . . 8 2.2.1 Particle Generation . . . . . . . . . . . . . . . . . . . . 8 2.2.2 The Pencil Beam . . . . . . . . . . . . . . . . . . . . . 9 2.3 The E391a Detector . . . . . . . . . . . . . . . . . . . . . . . 10 2.3.1 Electromagnetic Calorimeter . . . . . . . . . . . . . . . 11 2.3.2 Charged Veto . . . . . . . . . . . . . . . . . . . . . . . 14 2.3.3 Main Barrel . . . . . . . . . . . . . . . . . . . . . . . . 17 2.3.4 Front Barrel . . . . . . . . . . . . . . . . . . . . . . . . 21 2.3.5 Collar Counters . . . . . . . . . . . . . . . . . . . . . . 22 2.3.6 Back Anti . . . . . . . . . . . . . . . . . . . . . . . . . 24 2.3.7 Beam Hole Charged Veto . . . . . . . . . . . . . . . . . 25 2.4 Vacuum System . . . . . . . . . . . . . . . . . . . . . . . . . . 25 2.4.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . 27 2.4.2 PMT operation in vacuum . . . . . . . . . . . . . . . . 27 2.5 Triggering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 2.5.1 AmpDiscri module . . . . . . . . . . . . . . . . . . . . 29 2.5.2 Physics trigger . . . . . . . . . . . . . . . . . . . . . . 29 2.5.3 Other triggers . . . . . . . . . . . . . . . . . . . . . . . 32 2.5.4 Data Acquisition . . . . . . . . . . . . . . . . . . . . . 33 2.6 Data Sample . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 2.6.1 Data taking shifts . . . . . . . . . . . . . . . . . . . . . 34 3 Monte Carlo Simulation 36 3.1 Particle generation . . . . . . . . . . . . . . . . . . . . . . . . 36 3.2 KL propagation and decay . . . . . . . . . . . . . . . . . . . . 37 3.3 Decay modes and statistics . . . . . . . . . . . . . . . . . . . . 37 3.3.1 Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . 38 3.4 Energy deposit . . . . . . . . . . . . . . . . . . . . . . . . . . 38 3.5 Accidental activity . . . . . . . . . . . . . . . . . . . . . . . . 40 3.6 Combination of modes . . . . . . . . . . . . . . . . . . . . . . 40 4 Analysis Method 41 4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 4.2 Event Reconstruction . . . . . . . . . . . . . . . . . . . . . . . 42 4.2.1 Clustering routine . . . . . . . . . . . . . . . . . . . . . 42 4.2.2 Kinematic reconstruction . . . . . . . . . . . . . . . . . 43 4.2.3 Reconstruction results . . . . . . . . . . . . . . . . . . 52 4.3 Candidate Selection . . . . . . . . . . . . . . . . . . . . . . . . 52 4.3.1 Signal box . . . . . . . . . . . . . . . . . . . . . . . . . 52 4.3.2 0 region . . . . . . . . . . . . . . . . . . . . . . . . . . 53 4.4 Background Suppression . . . . . . . . . . . . . . . . . . . . . 53 4.4.1 Veto cuts . . . . . . . . . . . . . . . . . . . . . . . . . 54 4.4.2 Kinematic and MB cuts . . . . . . . . . . . . . . . . . 56 4.4.3 Cluster quality . . . . . . . . . . . . . . . . . . . . . . 60 4.4.4 0 tail . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 4.4.5 KL radius at the exit of collimator 6 . . . . . . . . . . 63 4.4.6 Selection results . . . . . . . . . . . . . . . . . . . . . . 63 5 Signal Extraction 66 5.1 Likelihood Method . . . . . . . . . . . . . . . . . . . . . . . . 66 5.1.1 Denition . . . . . . . . . . . . . . . . . . . . . . . . . 66 5.1.2 Background PDF . . . . . . . . . . . . . . . . . . . . . 67 5.1.3 Background normalization . . . . . . . . . . . . . . . . 69 5.1.4 Signal PDF . . . . . . . . . . . . . . . . . . . . . . . . 70 5.1.5 Fit results . . . . . . . . . . . . . . . . . . . . . . . . . 70 Upper Limit Estimation . . . . . . . . . . . . . . . . . . . . . 71 5.2.1 Systematic error study . . . . . . . . . . . . . . . . . . 71 5.2.2 Implementation of systematic errors . . . . . . . . . . . 75 5.2.3 Final tting results . . . . . . . . . . . . . . . . . . . . 75 5.3Counting Method . . . . . . . . . . . . . . . . . . . . . . . . . 77 5.4KL Flux . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 Conclusions and Prospects 81 6.1Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 6.2Prospects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 6.2.1 Increased data statistics { Run3 data set . . . . . . . . 82 6.2.2 Increased MC statistics . . . . . . . . . . . . . . . . . . 83 6.2.3 Finer CsI crystals { E14 experiment . . . . . . . . . . . 84 ! 0 Monte Carlo 89 Kinematic Fitting 92 | |
| dc.language.iso | en | |
| dc.subject | 準純量sgoldstino | zh_TW |
| dc.subject | K介子 | zh_TW |
| dc.subject | 衰變 | zh_TW |
| dc.title | 尋找中性K介子衰變至準純量sgoldstino粒子 | zh_TW |
| dc.title | Search for KL decay to light pseudoscalar sgoldstino at E391a | en |
| dc.type | Thesis | |
| dc.date.schoolyear | 96-1 | |
| dc.description.degree | 碩士 | |
| dc.contributor.oralexamcommittee | 王名儒(Min-Zu Wang),張寶棣(Pao-Ti Chang),何小剛(Xiao-Gang He) | |
| dc.subject.keyword | K介子,衰變,準純量sgoldstino, | zh_TW |
| dc.subject.keyword | KL decay,sgoldstino,E391a, | en |
| dc.relation.page | 88 | |
| dc.rights.note | 有償授權 | |
| dc.date.accepted | 2007-12-27 | |
| dc.contributor.author-college | 理學院 | zh_TW |
| dc.contributor.author-dept | 物理研究所 | zh_TW |
| 顯示於系所單位： | 物理學系 | |
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