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http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/6270完整後設資料紀錄
| DC 欄位 | 值 | 語言 |
|---|---|---|
| dc.contributor.advisor | 張寶棣(Pao-Ti Chang) | |
| dc.contributor.author | Yun-Han Lee | en |
| dc.contributor.author | 李昀翰 | zh_TW |
| dc.date.accessioned | 2021-05-16T16:24:38Z | - |
| dc.date.available | 2013-12-31 | |
| dc.date.available | 2021-05-16T16:24:38Z | - |
| dc.date.copyright | 2013-07-03 | |
| dc.date.issued | 2013 | |
| dc.date.submitted | 2013-06-20 | |
| dc.identifier.citation | [1] S.L. Glashow, J. Iliopoulos, L. Maiani, 1970.
[2] J. A. Aguilar-Saavedra and B. M. Nobre, Phys. Lett. B 553, 2003. [3] D. Atwood, L. Reina and A. Soni, Phys. Rev. D 55, 1997. [4] H. J. He and C. P. Yuan, Phys. Rev. Lett. 83, 1999. [5] CMS Physics TDR: Volume I (PTDR1), Detector Performace and Software, 2007. [6] Johan Alwall, Michel Herquet, Fabio Maltoni, Olivier Mattelaer, Tim Stelzer, 2011. [7] P. de Causmaecker, R. Gastmaxxs, W. Troost, and T.T. Wu, Phys. Lett. 105B, 215, 1981. [8] hep-ph/0603175, LU TP 06-13, FERMILAB-PUB-06-052-CD-T, 2006. [9] arXiv:1101.1652, TAUOLA for simulation of tau decay and production, 2011. [10] Z.Was, TAUOLA the library for tau lepton decay, and KKMC / KORALB / KORALZ /... status report, Nucl.Phys.Proc.Suppl. 98 (2001) 96 V102, doi:10.1016/S0920-5632(01)01200-2, arXiv:hep-ph/0011305. [11] Maryam Zeinali, Measurement of the Jet Energy Scale in the CMS experiment with the First LHC Proton Collisions, 2011 [12] J. A. Aguilar-Saavedra, Top flavor changing neutral coupling signals at a linear collider, Phys. Lett. B 502 (2001) 115, doi:10.1016/S0370-2693(01)00162- 9, arXiv:hep-ph/0012305. [13] G. Lu et al., Rare top quark decays t to cV in the topcolor assisted technicolor model, Phys. Rev. D 68 (2003) 015002, doi:10.1103/PhysRevD.68.015002, arXiv:hep-ph/0303122. [14] ATLAS Collaboration, A search for flavour changing neutral currents in top-quark decays in pp collision data collected with the ATLAS detector at sqrt(s) = 7 TeV. JHEP 1209 (2012) 139, doi:10.1007/JHEP09(2012)139, arXiv:1206.0257. [15] CMS Collaboration, The CMS experiment at the CERN LHC, JINST 03 (2008) S08004, doi:10.1088/1748-0221/3/08/S08004. [16] T. Han and J. L. Hewett, Top charm associated production in high-energy e+e collisions, Phys.Rev. D60 (1999) 074015, doi:10.1103/PhysRevD.60.074015, arXiv:hep-ph/9811237. [17] CMS Collaboration, Performance of b-jet identification in CMS, CMS Physics Analysisis Summary CMS-PAS-BTV-11-001, (2011). [18] Bernardo, Jose M.; Smith, Adrian F. M. (1994). Bayesian Theory. Wiley. ISBN 0-471-49464-X. | |
| dc.identifier.uri | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/6270 | - |
| dc.description.abstract | 在標準模型中，按照GIM機制的預測，以Z玻色子為媒介之跨世代衰變反應是被抑止的，在頂夸克的例子中，其反應率遠低於目前之測量範圍，但在其它模型中，該反應率可以目前之測量範圍。
我們使用了緊湊渺子線圈在2012年紀錄的質心能量為8 TeV之質子對撞數據，總通量約為19.5 fb-1，以尋找頂夸克衰變至Z玻色子與魅夸克(或上夸克)的事件。 在大強子對撞機實驗中，大多數頂夸克係成對產生，故我們以tt ‾→Wb+Zq之輕子性衰變為尋找標的，即W玻色子衰變至電子或渺子及對應的微中子，Z玻色子衰變為電子或渺子對。我們使用了b簇射(jet)標記，以配對衰變至Wb的頂夸克，以反b簇射標記配對衰變至Zq的頂夸克。在此選擇條件下，背景之主要組成為Ztt ‾以及WZ反應。 我們以b簇射標記法進行數據導向之背景分析，預測將觀測3.08±0.85±0.76個背景事件，與蒙地卡羅法之預測一致。 在數據中僅觀察到一個滿足選擇條件的事件，符合標準模型之預測；我們計算出t→Zq之衰變佔頂夸克衰變的百分率在95%之信心水準下不超過0.06%。 | zh_TW |
| dc.description.abstract | In the standard model, cross-generation interactions mediated by Z bosons, known as the flavor-changing neutral current (FCNC), are highly suppressed.
For top quark FCNC decay, the cross-section is far below the experimental limit. However, other models predict much higher cross-sections, and some of them are even within reach. Therefore, using the data sample corresponding to an integrated luminosity of 19.5 fb^−1 proton-proton collisions at a center-of-mass energy 8TeV , collected with the CMS detector at the LHC, we performed the search with the decay chain t‾t to Wb+Zq, where W decays to a charged lepton and a neutrino and Z decays to two charged leptons. The data-driven analysis using b-tagging method is performed with the estimated background being 3.08±0.85±0.76, which is consistent with the estimation of Monte-Carlo method. One event is observed in the data which is consistent with the expected background, and the upper limit of the branching fraction for t to Z+q is calculated as 0.06% at the 95% confidence level. | en |
| dc.description.provenance | Made available in DSpace on 2021-05-16T16:24:38Z (GMT). No. of bitstreams: 1 ntu-102-R00222028-1.pdf: 5809708 bytes, checksum: c8f4a1331b064ad5c86d9062312151a7 (MD5) Previous issue date: 2013 | en |
| dc.description.tableofcontents | 1 Introduction 13
1.1 The Standard Model . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 1.1.1 Quarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 1.1.2 Leptons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 1.1.3 Gauge Bosons . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 1.2 The Flavor-Changing Neutral Current of top decay . . . . . . . . . . 16 1.2.1 The two-Higgs doublet models . . . . . . . . . . . . . . . . . . 17 1.2.2 Supersymmetry models . . . . . . . . . . . . . . . . . . . . . . 17 1.2.3 Technicolour model . . . . . . . . . . . . . . . . . . . . . . . . 17 1.3 Proton-Proton Collisions . . . . . . . . . . . . . . . . . . . . . . . . . 17 1.4 Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 2 Experimental Apparatus 20 2.1 The Large Hadron Collider . . . . . . . . . . . . . . . . . . . . . . . . 20 2.2 The Compact Muon Solenoid . . . . . . . . . . . . . . . . . . . . . . 21 2.2.1 Coordinate Conventions . . . . . . . . . . . . . . . . . . . . . 22 2.2.2 Magnet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 2.2.3 Inner Tracking System . . . . . . . . . . . . . . . . . . . . . . 23 2.2.4 Muon System . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 2.2.5 Electromagnetic Calorimeter . . . . . . . . . . . . . . . . . . . 25 2.2.6 Hadron Calorimeter . . . . . . . . . . . . . . . . . . . . . . . . 26 2.2.7 Trigger System . . . . . . . . . . . . . . . . . . . . . . . . . . 27 3 Physical Object Reconstruction 29 3.1 Track Reconstruction . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 3.2 Vertex Reconstruction . . . . . . . . . . . . . . . . . . . . . . . . . . 30 3.3 Electron Reconstruction . . . . . . . . . . . . . . . . . . . . . . . . . 31 3.4 Muon Reconstruction . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 3.5 Particle Flow and Transverse Missing Energy . . . . . . . . . . . . . . 34 3.6 Jet Reconstruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 3.7 b tagging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 4 Data and Monte Carlo Samples 39 4.1 Pile-Up Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 5 Event Selection 44 5.1 High Level Trigger . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 5.2 Vertex Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 5.3 Electron Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 5.4 Muon Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 5.5 Jet Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 5.6 Z Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 5.7 MET and W Selection . . . . . . . . . . . . . . . . . . . . . . . . . . 50 5.8 Top Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 6 Background Analysis 54 6.1 Data-Driven Method . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 6.2 MC Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 7 Systematic Uncertainty 61 7.1 Luminosity Measurement . . . . . . . . . . . . . . . . . . . . . . . . . 61 7.2 Cross Sections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 7.3 Lepton Isolation and Selections . . . . . . . . . . . . . . . . . . . . . 62 7.4 Jet Energy Scale and Jet Energy Resolution . . . . . . . . . . . . . . 62 7.5 MET Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 7.6 Parton Distribution Function . . . . . . . . . . . . . . . . . . . . . . 63 7.7 MadGraph Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . 64 7.8 High Level Trigger . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 7.9 Pile-Up Reweighting . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 7.10 Monte Carlo Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . 66 7.11 b-tagging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 7.12 Systematic for Data-Driven background analysis . . . . . . . . . . . . 66 8 Summary 70 | |
| dc.language.iso | en | |
| dc.title | 在8 TeV質心能量的質子對撞實驗中尋找頂夸克透過Z玻色子及魅夸克（或上夸克）衰變的事件 | zh_TW |
| dc.title | Search for top decays through flavor changing neutral current process, t→Z+q, in pp collisions at √s=8 TeV | en |
| dc.type | Thesis | |
| dc.date.schoolyear | 101-2 | |
| dc.description.degree | 碩士 | |
| dc.contributor.oralexamcommittee | 陳凱風(Kai-Feng Chen),陳俊瑋(Chen, Jiunn-Wei),熊怡(Yee, Hsiung),侯維恕(Wei-Shu, Hou) | |
| dc.subject.keyword | GIM 機制,大強子對撞機,緊湊渺子線圈,味變中性流,頂夸克, | zh_TW |
| dc.subject.keyword | GIM mechanism,LHC,CMS,FCNC,top, | en |
| dc.relation.page | 80 | |
| dc.rights.note | 同意授權(全球公開) | |
| dc.date.accepted | 2013-06-20 | |
| 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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