none｜國立中央大學博碩士論文系統

簡易檢索 / 詳目顯示

回結果列表

研究生：	陳冠昕 Kuan-Hsin Chen
論文名稱：	Measurement of Zγ production in 5 fb-1 of pp collisions at √s = 7 TeV with the CMS detector
指導教授：	郭家銘 Chia-Ming Kuo
口試委員:
學位類別：	博士 Doctor
系所名稱：	理學院 - 物理學系 Department of Physics
論文出版年：	2014
畢業學年度：	103
語文別：	英文
論文頁數：	126
中文關鍵詞：	光子、Z玻色子、標準模型、高能物理
外文關鍵詞：	CMS, LHC, Standard Model, Zγ
相關次數：	點閱：8 下載：0
分享至:	分享至facebook 分享至twitter

查詢本校圖書館目錄查詢臺灣博碩士論文知識加值系統勘誤回報

本篇論文呈現了使用質子-質子對撞、中心能量在7 TeV的 Zγ 生產截面積的量測。其使用的數據為由LHC產生，由CMS偵測器所蒐集得到，其累積光度為5.0 fb-1。此產生截面積量測是針對光子橫向能量大於15 GeV、光子與電子空間分離ΔR(e,γ)大於0.7且電子對的恆定質量大於50 GeV。量測的碰撞產生截面為5.20 ± 0.32(系統誤差) ± 0.32(系統誤差) ± 0.11(光度誤差) pb。結果與標準模型的預測相吻合。

Measurements of Zγ production cross section in proton-proton collisions at √s =7 TeV are presented. The results are based on data recorded by the CMS detector
at the LHC that correspond to an integrated luminosity of 5.0 fb−1. The cross sections are measured for photon transverse energy > 15 GeV, and for separations
between photons and ﬁnal-state electrons in the pseudorapidity-azimuthal plane of ΔR(e, γ) > 0.7 in eeγ ﬁnal state. A dielectron invariant mass requirement of di-electron pair > 50 GeV is imposed. The σ(pp → Zγ) × B(Z → e+ e−) is measured to be 5.20 ± 0.13(stat) ± 0.32(syst) ± 0.11(lum) pb. The results are consistent with predictions from the standard model.

Introduction 1
The Experimental Setup 3
1 The Large Hadron Collider . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 The Luminosity of LHC . . . . . . . . . . . . . . . . . . . . . 5
2 CMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1 The coordinate of CMS detector . . . . . . . . . . . . . . . . . 6
2.2 Magnet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.3 Tracker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.4 Electromagnetic Calorimeter . . . . . . . . . . . . . . . . . . . 10
2.5 Hardronic Calorimeter . . . . . . . . . . . . . . . . . . . . . . 15
2.6 Muon Detectors . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Overview of Zγ Production 18
1 Standard Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2 Electroweak Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3 Zγ production and anomalous triple gauge coupling . . . . . . . . . . 22
3.1 Standard Model Zγ production . . . . . . . . . . . . . . . . . 22
3.2 Anomalous triple gauge coupling . . . . . . . . . . . . . . . . 23
Analysis Method 25
1 Data and Monte Carlo samples . . . . . . . . . . . . . . . . . . . . . 25
1.1 Data samples . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
1.2 Monte Carlo samples . . . . . . . . . . . . . . . . . . . . . . . 25
2 Object selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.1 Triggers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.2 Electron selection . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.3 Tag and Probe Method . . . . . . . . . . . . . . . . . . . . . . 32
2.4 Photon selection . . . . . . . . . . . . . . . . . . . . . . . . . 44
3 Data-Driven Background Methods . . . . . . . . . . . . . . . . . . . . 50
3.1 The template method . . . . . . . . . . . . . . . . . . . . . . . 50
3.2 The ratio method . . . . . . . . . . . . . . . . . . . . . . . . . 57
Measurement of Zγ Production Cross-Section 60
1 Event selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
2 Determination of backgrounds . . . . . . . . . . . . . . . . . . . . . . 70
3 Systematic uncertainties . . . . . . . . . . . . . . . . . . . . . . . . . 76
3.1 Systematic uncertainty on N sig . . . . . . . . . . . . . . . . . 76
3.2 Systematic uncertainty on F = A s ·  MC . . . . . . . . . . . . 76
3.3 Systematic uncertainty ρ eff . . . . . . . . . . . . . . . . . . . 77
3.4 Systematic uncertainty on the background estimation . . . . . 78
3.5 Systematic uncertainty on lluminosity . . . . . . . . . . . . . . 79
3.6 Summary of systematic uncertainties . . . . . . . . . . . . . . 79
4 Measurement of the Zγ cross section . . . . . . . . . . . . . . . . . . 82
4.1 Production cross section . . . . . . . . . . . . . . . . . . . . . 82
4.2 Results of Zγ cross section . . . . . . . . . . . . . . . . . . . . 83
Conclustion 86
A Anomalous triple gauge couplings in Zγ production 88
B Cut based photon identiﬁcation for 2012 dataset 90
B.1 Event selection criteria . . . . . . . . . . . . . . . . . . . . . . . . . . 90
B.2 Tag and probe method . . . . . . . . . . . . . . . . . . . . . . . . . . 91
                                

[1] Christiane Lefvre. The cern accelerator complex. complexe des acclrateurs du
cern. https://cdsweb.cern.ch/record/1260465?ln=en.
[2] ”https://twiki.cern.ch/twiki/bin/view/CMSPublic/LumiPublicResults”.
[3] CMS Collaboration. Ecal detector performance, 2011 data. CMS-DP-2012/007,
2012.
[4] CMS collaboration. Cms standard model physics results.
https://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResultsSMP.
[5] CMS collaboration. Observation of a new boson at a mass of 125 gev with the
cms experiment at the lhc. Physics Letters B, 716(1):30 – 61, 2012.
[6] ATLAS collaboration. Observation of a new particle in the search for the stan-
dard model higgs boson with the atlas detector at the lhc. Physics Letters B,
716(1):1 – 29, 2012.
[7] LEP Electroweak Working Group. A Combination of Preliminary Electroweak
Measurements and Constraints on the Standard Model. 2006.
[8] P. Acciarri. Measurement of energetic single photon production at LEP. Phys.
Lett. B, 346:190, 1995.
[9] P. Achard. Study of the e + e
− → Zγ process at LEP and limits on triple neutral-
gauge-boson couplings. Phys. Lett. B, 597:119, 2004.
[10] G. Abbiendi. Study of z pair production and anomalous couplings in e + e
−
colli-
sions at
√
s between 190 gev and 209 gev. Eur. Phys. J. C, 32:303, 2003.
[11] T. Aaltonen et al. Measurement of Zγ production in p¯p collisions at
√
s = 1.96
TeV. Phys. Rev. D, 82:031103, 2010.
[12] V. M. Abazov et al. Zγ production and limits on anomalous ZZγ and Zγγ
couplings in p¯p collisions at
√
s = 1.96 TeV. Phys. Lett. B, 653:378, 2007.
[13] V. M. Abazov et al. Measurement of the Zγ → ν¯νγ production cross section and
limits on anomalous ZZγ and Zγγ couplings in p¯p collisions at
√
s = 1.96 TeV.
Phys. Rev. Lett., 102:201802, 2009.
[14] S. Chatrchyan et al. Measurement of W
+
W
−
production and search for the higgs
boson in pp collisions at
√
s = 7tev. Phys. Lett. B, 699:25, 2011.
[15] S. Chatrchyan et al. Measurement of wγ and zγ production in pp collisions at
√
s = 7tev. Phys. Lett. B, 701:535, 2011.
[16] G. Aad et al. Measurement of wγ and zγ production in pp collisions at
√
s = 7tev
with the atlas detector at the lhc. Phys. Rev. D, 87:112003, 2013.
[17] O. Bruning, H. Burkhardt, and S. Myers. The large hadron collider.
Prog.Part.Nucl.Phys., 67:705–734, 2012.
[18] G. Aad et al. The ATLAS experiment at the cern large hadron collider. JINST,
3:S8003, 2008.
[19] S. Chatrchyan et al. The CMS experiment at the CERN LHC . JINST,
3:S08004, 2008.
[20] Jr. Alves, A. Augusto et al. The LHCb detector at the LHC . JINST, 3:S8005,
2008.
[21] K. Aamodt et al. The alice detector at the LHC . JINST, 3:S8002, 2008.
[22] A.L. Macpherson. LHC AVAILABILITY AND PERFORMANCE
IN 2011 . http://indico.cern.ch/getFile.py/access?contribId=
2&sessionId=0&resId=2%&materialId=paper&confId=164089, 2012.
[23] CMS: The electromagnetic calorimeter. Technical design report. 1997.
[24] http://pdg.lbl.gov/.
[25] CMS Collaboration. Ecal 2010 performance results. CMS-DP-2011/008, 2011.
[26] CMS Collaboration. Performance of cms muon reconstruction in pp collision
events at sqrt(s) = 7 tev. JINST, 7:P10002, 2013.
[27] A. Azatov and J. Galloway. Electroweak symmetry breaking and the higgs boson:
Confronting theories at colliders. Int.J.Mod.Phys., A28:1330004, 2013.
[28] S.L Glashow. Nucl. Phys, 22:579, 1961.
[29] S. Weinberg. Phys. Rev, Lett., 19:1264, 1967.
[30] A. Salam. Proceedings of the eight nobel symposium. 1968.
[31] U. Baur and E. Berger. Probing the weak-boson sector in Zγ production at
hadron colliders. Phys. Rev., D47:4889, 1993.
[32] J. Alwall, M. Herquet, F. Maltoni, and O. Mattelaer. Madgraph 5: Going
beyond. JHEP, 06:128, 2011.
[33] J. M. Campbell, R. K. Ellis, and C. Williams. Vector boson pair production at
the lhc. JHEP, 07:018, 2011.
[34] J. M. Campbell and R. K. Ellis. Update on vector boson pair production at
hadron colliders. Phys. Rev. D, 60:113006, 1999.
[35] J. Alcaraz Maestre et al. Updated measurements of the inclusive w and z cross
sections at 7 tev. CMS Note, 2010/264, 2010.
[36] Generic Tag and Probe Tool for Measuring Eﬃciency at CMS with Early Data.
CMS Analysis Note, AN-2009/111, 2009.
[37] W. Andrews et al. Search for higgs boson decays to two w bosons in the fully
leptonic ﬁnal state with full 2011 pp dataset at
√
s=7 TeV. CMS Note, 2011/432,
2011.
[38] https://twiki.cern.ch/twiki/bin/view/CMS/PileupReweighting.
[39] CMS Collaboration. Phys. Rev. D, 89:092005, May 2014.
[40] K. Cranmer. Kernel estimation in high-energy physics. Comput. Phys. Commun.,
136:198, 2001.
[41] Measurement of inclusive Wγ and Zγ cross sections and limits on anomalous
trilinear gauge boson couplings at 7 TeV. CMS Analysis Note, AN-2010-279,
2010.
[42] S. Chatrchyan. Search for the standard model higgs boson decaying into two
photons in pp collisions at
√
s = 7tev. Phys. Lett. B, 710:403, 2012.
[43] Jan Veverka. Studes of Zγ production and constraints on anomalous triple gauge
couplings in pp collisions at
√
s = 7TeV . PhD thesis, 2013.
[44] S. Chatrchyan. Observation of a new boson with mass near 125 gev in pp colli-
sions at
√
s = 7 and 8 tev. JHEP, 06:081, 2013.
[45] S. Chatrchyan et al. Measurement of the inelastic proton-proton cross section at
√
s = 7tev. Phys. Lett. B, 722:5, 2013.
[46] P. M. Nadolsky, H.-L. Lai, Q.-H. Cao, J. Huston, J. Pumplin, D. Stump, W.-
K. Tung, and C.-P. Yuan. Implications of CTEQ global analysis for collider
observables. Phys. Rev. D, 78:013004, 2008.
[47] Absolute calibration of the luminosity measurement at cms: Winter 2012 update.
CMS Physics Analysis Summary CMS-PAS-SMP-12-008, 2012.
[48] G. Cowan, K. Cranmer, E. Gross, and O. Vitells. Asymptotic formulae for
likelihood-based tests of new physics. Eur. Phys. J. C, 71:1554, 2011.
[49] T. Gleisberg, S. Hoeche, F. Krauss, M. Schonherr, S. Schumann, F. Siegert, and
J. Winter. Event generation with sherpa 1.1. JHEP, 02:007, 2009.
[50] CMS Collaboration. Commissioning of the Particle-ﬂow Event Reconstruction
with the ﬁrst LHC collisions recorded in the CMS detector. Technical Report
CMS-PAS-PFT-10-001, 2010.
[51] CMS Collaboration. Commissioning of the Particle-Flow reconstruction in
Minimum-Bias and Jet Events from pp Collisions at 7 TeV. (CMS-PAS-PFT-
10-002), 2010.

簡易檢索 / 詳目顯示

相關論文